Cannabis use disorder is declining among young adolescents and young adults

October 31, 2019

Science Daily/Columbia University's Mailman School of Public Health

The prevalence of cannabis use disorder decreased in 2002 to 2016 among frequent users, according to a new study conducted at Columbia University Mailman School of Public Health. Changes in social attitudes and the traits of frequent users may explain the decline, according to researchers. This is one of the first studies to examine the general health profile of people using cannabis daily or almost daily and the trends in the prevalence of cannabis use disorder in this population. The findings are online in the journal Drug and Alcohol Dependence.

"Contrary to expectations, the frequency of cannabis use disorder among people reporting daily/almost daily use decreased significantly between 2002-2016, said Silvia Martins, MD, PhD, associate professor of Epidemiology at Columbia Mailman School. "The findings contradict the predominating hypothesis that the prevalence of DSM-IV CUD would be stable, or increase, among those using with this regularity."

Data from the National Survey on Drug Use and Health for 2002-2016 included 22,651 individuals using cannabis 300+ days in the past year. Cannabis use disorder was defined using DSM-IV criteria for cannabis abuse and/or dependence. Age categories included: 12-17, 18-25, and 26?and older.

From 2002-2016, the prevalence of cannabis use disorder among people reporting daily or almost daily use decreased across all age groups -- by 27 percent in adolescents, by 30 percent in ages 18-25, and by 37.5 percent for those age 26 and older.

"There could be several reasons behind these declining rates," noted Martins, who is also director, Substance Use Epidemiology Unit at Columbia. "First, the new national cannabis policy environment, with 33 states legalizing medical use and 10 states allowing recreational use of cannabis may have played a role in reducing stigma and perceptions of risk associated with cannabis use. "Secondly, increasing legalization may also be associated with changes in social attitudes resulting in fewer conflicts with relatives and friends around cannabis use."

For all age groups, there was no evidence of any significant reductions in the perceived need for mental health treatment among individuals using cannabis regularly (daily/near daily), or the prevalence of health problems as indicated by doctors.

The researchers also did not find evidence of significant reductions in prevalences of past-year health problems when examining health clusters separately including mental health, respiratory, digestive, cardiovascular, and infectious diseases health problems.

In contrast, there were significant decreases in self-reported driving under the influence of illegal drugs including alcohol across all age groups, ranging from a 26 percent, 29 percent and 38 percent change in adolescents, those 18-24 and age 26 and older, respectively.

https://www.sciencedaily.com/releases/2019/10/191031100512.htm

Teen marijuana use may have next-generation effects

October 28, 2019

Science Daily/University of Washington

A new study shows how a parent's use of marijuana, past or present, can influence their child's substance use and well-being.

Substance use at any age has consequences. Studies frequently cite the negative impacts -- and occasionally tout some benefits of limited consumption -- of alcohol and marijuana.

What is less known is how patterns of alcohol or marijuana use in one phase of life can affect the next generation, even long after an individual has stopped using.

A new study by the University of Washington's Social Development Research Group shows how a parent's use of marijuana, past or present, can influence their child's substance use and well-being.

"The really important takeaway is that parent history of marijuana use is an important risk factor for kids," said Marina Epstein, lead author of the study and a project director at the SDRG, which is part of the UW School of Social Work.

The study, published online Sept. 9 in the journal Psychology of Addictive Behaviors, builds off previous work that had grouped participants according to whether, when and how often they used, and examined impacts to their health and behavior. That study found four distinct patterns: "nonusers"; "adolescent-limited" (confined to only that period of life); "late onset" (starting in their late teens, early 20s); and "chronic" (ongoing and frequent). This study is based on a subset of the original participants who have become parents, and has linked parents' past use of marijuana to their children's use of and attitudes toward alcohol and marijuana, other problem behavior, and school achievement.

The original investigation involving parents began in the 1980s when the now-adults were in fifth grade at several Seattle elementary schools. Researchers have followed the participants ever since. In 2002, when the participants were 27, SDRG recruited those who had become parents and began interviewing their children about alcohol beginning at age 6, and marijuana starting at age 10. To date, 360 children completed interviews between the ages of 10 and 20.

Children and teens of chronic users were most likely to use alcohol and marijuana themselves, as researchers had predicted. But what came as more of a surprise was the behavior of children whose parents had primarily used during adolescence: Compared to the children of nonusers, children of adults in the "adolescent-limited" group were more than 2.5 times as likely to use marijuana and 1.8 times as likely to use alcohol. This was true even after parents' current marijuana use was accounted for.

In comparison, children of chronic users were nearly 4.5 times as likely to use marijuana, and 2.75 times as likely to use alcohol, as children of nonusers.

Children in the "late-onset" group, as it turned out, were least likely to use marijuana, as were children of nonusers. They did, however, have lower grades.

"Using marijuana in adolescence is associated with a host of other problems in the present and later into adulthood," said Epstein, who was the lead author on the earlier paper that established the marijuana usage patterns. "Now we see that echoing through to their children."

According to that prior study, people who used marijuana during their teen years tended to have poorer functioning during the period in which they were actively using, and, by their early 30s, to have lower academic and economic outcomes than people who started using as adults, or who never used.

Chronic users had the worst outcomes in terms of health and quality of life, Epstein added: Poor mental health, lower academic outcomes, less financial stability and greater tendency of criminal and/or risky behaviors were associated with frequent, lifetime marijuana use.

The researchers need additional studies to uncover reasons for the relatively high usage patterns among children in the adolescent-limited group. There may be a connection between a parent's use during adolescence, for example, and their subsequent attitudes toward substance use among teenagers in general, Epstein said.

Today, 33 states have legalized marijuana in some form, often for medical purposes, and of those, 11 states -- including Washington -- have legalized it for recreational use. Those developments have implications for how parents talk to their children about marijuana and how health care providers talk to patients. Even a routine review of a child's health history could include a question about a parent's history of marijuana use -- just to consider the potential impact on the child, Epstein said.

"Now that marijuana is legal, we have to be able to talk to parents about how they're using, and to be more specific -- how much, how often, whether this is lifelong pattern," said Epstein. "The landscape of marijuana is changing, and we have to be mindful of it."

https://www.sciencedaily.com/releases/2019/10/191028164418.htm

Teens are using a highly potent form of marijuana

August 26, 2019

Science Daily/Arizona State University

Nearly one in four Arizona teens have used a highly potent form of marijuana known as marijuana concentrate, according to a new study by Arizona State University researchers.

Among nearly 50,000 eighth, 10th, and 12th graders from the 2018 Arizona Youth Survey, a biennial survey of Arizona secondary school students, one-third (33%) had tried some form of marijuana, and nearly a quarter (24%) had tried marijuana concentrate.

Marijuana concentrates have about three times more THC, the constituent of marijuana that causes the "high," than a traditional marijuana flower. This is concerning because higher doses of THC have been linked to increased risk of marijuana addiction, cognitive impairment and psychosis, said the study's lead researcher, Madeline Meier, an ASU assistant professor of psychology.

The research team also found that teens who used concentrates had more risk factors for addiction. The researchers compared teens who had used marijuana concentrates with teens who had used some form of marijuana but not marijuana concentrates and teens who had never used any form of marijuana on known risk factors for addiction, such as lower perceived risk of harm of marijuana, peer substance use, parental substance use, academic failure and greater perceived availability of drugs in the community. They found that teens who had used marijuana concentrates were worse off on every addiction risk factor.

"This is important because it shows that teens who have a diverse array of risk factors for developing marijuana addiction may be further amplifying their risk for addiction by using high-THC marijuana concentrates," explained study co-author, Dustin Pardini, an associate professor in ASU's School of Criminology & Criminal Justice.

The study "Cannabis Concentrate Use in Adolescents," is published in the early online edition (Aug. 26, 2019) of Pediatrics.

The team -- which includes ASU researchers Meagan Docherty, School of Criminology & Criminal Justice; Scott Leischow, College of Health Solutions; and Kevin Grimm, Department of Psychology -- also found that teens who had used concentrates had much higher rates of e-cigarette use. One explanation for this might be that teens are using e-cigarettes to vape marijuana concentrate, according to Meier. Earlier studies, including those by Meier, have shown that youth put marijuana in e-cigarettes to conceal their marijuana use.

"Vaping marijuana can be passed off as nicotine vaping," Meier explained.

This finding reinforces the recent decision by the Food and Drug Administration to impose new restrictions on e-cigarettes and their constituents as a means of reducing marijuana use, according to the researchers.

Marijuana concentrates don't look like the traditional marijuana flower. Concentrates can look like wax, oil, or a brittle substance that shatters easily.

"What concerns me most is that parents might have no idea that their child is using marijuana, especially if their child is using marijuana concentrate," said Meier. "Marijuana is not harmless, particularly for adolescents."

Meier's earlier research suggests that frequent marijuana use from adolescence through adulthood is associated with IQ decline. Pardini's prior research has linked regular marijuana use during adolescence with the emergence of persistent subclinical psychotic symptoms.

The researchers' next steps are to ascertain if concentrate users do in fact exhibit higher rates of addiction, cognitive impairment and psychosis.

https://www.sciencedaily.com/releases/2019/08/190826092256.htm

About 44% of high school seniors who misuse prescription drugs have multiple drug sources

July 17, 2019

Science Daily/University of Michigan

Roughly 11% of high school seniors reported prescription drug misuse during the past year, and of those, 44% used multiple supply sources, according to a pair of University of Michigan studies.

More than 70% of adolescents who obtained prescription drugs from multiple sources had a substance use disorder -- involving prescription medications, other drugs and alcohol -- within the previous year.

The national average for a substance use disorder for all adolescents is 5%, said senior author Sean Esteban McCabe, a professor at the U-M School of Nursing.

Both studies, published in the July issue of the Journal of the American Academy of Child and Adolescent Psychiatry, found that adolescents using multiple sources for prescription medications were at high risk for other substance use and substance use disorders, among other disturbing patterns.

One study identified sources of misuse for three classes of prescription drugs -- opioids, stimulants and tranquilizers -- and the differences in motives and behavior among 18,549 high school seniors. The other study identified sources of controlled medications and related behaviors in 103,920 adolescents ages 12 to 17.

A "very concerning" finding is that 30% of prescription drug misusers took their own leftover medication, with girls more likely to take leftovers than boys, said McCabe, who is also co-director of the U-M Center for the Study of Drugs, Alcohol, Smoking and Health. Boys were more likely to obtain prescription drugs from friends or purchase them.

The most common sources for prescription drugs for 12-to-17-year-olds were getting them free from friends and relatives, physician prescriptions for opioids, and buying stimulants and tranquilizers illegally.

"These adolescents are most in need of intervention to address their substance use and any other medical and mental health issues," said Ty Schepis, associate professor at Texas State University and lead author of one of the studies.

This is the first known research to look at adolescent misuse of leftover medications across these three prescription drug classes, McCabe said.

"The implications from these two studies could not be clearer," McCabe said. "Parents, public health experts and clinicians must rally to address this problem. There is a critical need for clinical workforce training to support clinic and school-based education, screening, prevention and early intervention."

https://www.sciencedaily.com/releases/2019/07/190717142636.htm

Teens abusing painkillers are more likely to later use heroin

July 8, 2019

Science Daily/University of Southern California

It's an unforeseen side effect of the nation's opioid epidemic: Adolescent heroin users.

 A USC study in the July 8 issue of JAMA Pediatrics shows that teens who use prescription opioids to get high are more likely to start using heroin by high school graduation.

"Prescription opioids and heroin activate the brain's pleasure circuit in similar ways," said senior author Adam Leventhal, a professor of preventive medicine and psychology and director of the USC Institute for Addiction Science at the Keck School of Medicine of USC. "Teens who enjoy the 'high' from prescription opioids could be more inclined to seek out other drugs that produce euphoria, including heroin."

Leventhal said the study, conducted from 2013-2017, is the first to track prescription opioid and heroin use in a group of teens over time. In 2017, 9% of the nation's 47,600 opioid overdose deaths occurred in people under the age of 25, according to data from the Centers for Disease Control and Prevention. In addition to overdose, health risks of heroin use are devastating and include severe addiction, hepatitis C, HIV and other infections.

Using twice-yearly surveys to track high schoolers' use of various drugs, researchers followed 3,298 freshmen from 10 Los Angeles-area high schools through their senior year. Participants were asked about their previous and current use of prescription painkillers -- such as Vicodin, Oxycontin and Percocet -- to get high.

The researchers also asked the students if they used heroin or other substances like marijuana, alcohol, cigarettes, methamphetamine and inhalants. They made statistical adjustments to account for differences in family environment, psychological disposition, family history of substance use and other factors associated with nonmedical prescription opioid use.

Of the nearly 3,300 students in the study, 596 reported using prescription opioids to get high during the first 3.5 years of high school. The researchers found that prescription painkiller use made a big difference in who later used heroin: 13.1% of current prescription opioid users and 10.7% of previous prescription opioid users went on to use heroin by the end of high school. Only 1.7% of youth who did not use prescription opioids to get high had later tried heroin by the end of high school.

"Adolescents are sometimes overlooked in the opioid epidemic discussion," said first author Lorraine Kelley-Quon, a pediatric surgeon and assistant professor of surgery and preventive medicine at Children's Hospital Los Angeles and the Keck School of Medicine. "The association between nonmedical opioid use and later heroin use in youth is concerning and warrants further research and health policy interventions."

To further confirm their results, the researchers also evaluated whether marijuana, alcohol, and methamphetamine use were linked to later heroin use. But the association between prescription opioids and heroin use was stronger than the associations for heroin use with other substances.

"While we can't definitively conclude that there is a cause-and-effect relation, there may be something unique about opioid drugs that makes youths vulnerable to trying heroin," Leventhal said. "The results do not appear to be driven by the tendency of some teens to act out, rebel, or experiment with many types of drugs."

https://www.sciencedaily.com/releases/2019/07/190708112504.htm

Synthetic version of CBD treats seizures in rats

May 28, 2019

Science Daily/University of California - Davis

A synthetic, non-intoxicating analogue of cannabidiol (CBD) is effective in treating seizures in rats, according to research by chemists at the University of California, Davis.

The synthetic CBD alternative is easier to purify than a plant extract, eliminates the need to use agricultural land for hemp cultivation, and could avoid legal complications with cannabis-related products. The work was recently published in the journal Scientific Reports.

"It's a much safer drug than CBD, with no abuse potential and doesn't require the cultivation of hemp," said Mark Mascal, professor in the UC Davis Department of Chemistry. Mascal's laboratory at UC Davis carried out the work in collaboration with researchers at the University of Reading, U.K.

Products containing CBD have recently become popular for their supposed health effects and because the compound does not cause a high. CBD is also being investigated as a pharmaceutical compound for conditions including anxiety, epilepsy, glaucoma and arthritis. But because it comes from extracts of cannabis or hemp plants, CBD poses legal problems in some states and under federal law. It is also possible to chemically convert CBD to tetrahydrocannabinol (THC), the intoxicating compound in marijuana.

8,9-Dihydrocannabidiol (H2CBD) is a synthetic molecule with a similar structure to CBD. Mascal's laboratory developed a simple method to inexpensively synthesize H2CBD from commercially available chemicals. "Unlike CBD, there is no way to convert H2CBD to intoxicating THC," he said.

One important medical use of cannabis and CBD is in treatment of epilepsy. The U.S. Food and Drug Administration has approved an extract of herbal CBD for treating some seizure conditions and there is also strong evidence from animal studies.

The researchers tested synthetic H2CBD against herbal CBD in rats with induced seizures. H2CBD and CBD were found to be equally effective for the reduction of both the frequency and severity of seizures.

Mascal is working with colleagues at the UC Davis School of Medicine to carry out more studies in animals with a goal of moving into clinical trials soon. UC Davis has applied for a provisional patent on antiseizure use of H2CBD and its analogues, and Mascal has founded a company, Syncanica, to continue development.

https://www.sciencedaily.com/releases/2019/05/190528140107.htm

Growing up high: Neurobiological consequences of adolescent cannabis use

Canadian neuroscientists offer insights into the long-term effects of adolescent cannabis use

May 26, 2019

Science Daily/Canadian Association for Neuroscience

About one in five Canadian adolescents uses cannabis (19% of Canadians aged 15-19), and its recent legalization across the country warrants investigation into the consequence of this use on the developing brain. Adolescence is associated with the maturation of cognitive functions, such as working memory, decision-making, and impulsivity control. This is a highly vulnerable period for the development of the brain as it represents a critical period wherein regulatory connection between higher-order regions of the cortex and emotional processing circuits deeper inside the brain are established. It is a period of strong remodeling, making adolescents highly vulnerable to drug-related developmental disturbances. Research presented by Canadian neuroscientists Patricia Conrod, Steven Laviolette, Iris Balodis and Jibran Khokhar at the 2019 Canadian Neuroscience Meeting in Toronto on May 25 featured recent discoveries on the effects of cannabis on the adolescent brain.

Dr. Patricia Conrod, at Université de Montréal, studied the year-to-year changes in alcohol and cannabis use and cognitive function in a sample of adolescents consisting of 5% of all students entering high school in 2012 and 2013 in the Greater Montreal region (a total of 3,826 7th grade students). Students were assessed annually for 4 years on alcohol and cannabis use, and their cognitive function was evaluated using computarized cognitive tests. The researchers found substance use to be linked to low cognitive functioning, a finding that could be indicative of an underlying common vulnerability. Cannabis use was linked to impairments in working memory and inhibitory control, which is required for self-control. Cannabis use was also linked to deficits in memory recall and perceptual reasoning. Alcohol use was not linked to impairments in these cognitive functions, suggesting cannabis could have more long-term effects than alcohol.

More recently Dr. Conrod's team analysed the sex difference in cannabis response in the same sample of adolescents. Preliminary data indicates that cannabis use had a stronger effect on the memory functions of male students than female students. Both sexes were however, equally affected by cannabis on inhibitory control. These results help identify at-risk youth groups and target them for early intervention and information.

Dr. Steven Laviolette presented research on the effect the primary psychoactive component of cannabis, delta-9-tetrahydrocannabinol or THC, on the adolescent brain, in rodent animal models. His team demonstrated that adolescent exposure to THC induces changes in specific a region of the brain called the prefrontal cortex (PFC) and in a brain circuit, the mesolimbic pathway, that closely resemble the abnormalities observed in schizophrenia. Furthermore, adolescent THC exposure also caused affective and cognitive abnormalities including deficits in social interactions, memory processing and anxiety regulation.

Interestingly, Dr. Laviolette's team found that administration of drugs that restore normal PFC function in early adulthood could reverse the effects of adolescent THC exposure. They also demonstrated that co-administering THC with drugs that prevent the THC-induced disruption in brain signaling pathways prevented the development of schizophrenia-like effects. These results offer insights into ways to prevent or reverse THC-induced brain signaling defects in adolescents.

Dr. Iris Balodis, from McMaster University, investigates the mechanisms that motivate individuals to act and make decisions that can go against a person's best interest, as seen in people suffering from addiction. To compare decision-making in individuals suffering from cannabis addiction (also called cannabis use disorder) to healthy controls, Dr. Balodis used an effort-based decision-making test, which explores how much effort and individual is willing to make to receive a given reward. Participants are given a choice between an easy task or a hard task in which they can gain varying amounts of money (for example, pressing a lever a number within a certain time limit). During the administration of this test, Dr. Balodis and her team looked at differences in activity in different brain regions by functional magnetic resonance imaging. Initial findings suggest that there are differences in encoding the value of the reward (money received) and of the effort cost (amount of work done) in individuals addicted to cannabis relative to healthy controls. These were revealed by differences in activation of specific brain regions known to be important for motivation. This information could be key to finding cannabis addiction vulnerability factors.

Adolescent cannabis use is associated with behavioral changes related to reward and motivation in humans. Paradoxically, this use has both been suggested to increase motivation for other drug use (the gateway hypothesis) and a potential "amotivation syndrome" in which individuals are less willing to expend effort to receive a reward. It is not known whether adolescent cannabis use causes either of these responses, or if cannabis use is rather a symptom of a pre-existing state that results in these behaviours. In order to better understand the long-term effects of adolescent cannabis exposure on the brain, Dr. Jibran Khokhar, from the University of Guelph, studied the effect of THC exposure in adolescent rats on their adult behaviour. In this study, adolescent THC exposure differentially impacted instrumental (decreased lever pressing) and Pavlovian learning (increased sign-tracking). These rats also showed differences in other reward-related behaviors. These behavioural changes were accompanied by changes in the connection between different regions of the brain, including those involved in encoding reward and motivation. These results suggest adolescent cannabis exposure in rats can produce long-lasting changes in brain circuitry which might contribute to the behavioral changes observed after cannabis exposure.

Taken together, the research results presented in this symposium help decipher the links between cannabis use and long-lasting changes in the brain, which underlie changes in behaviour in adolescent humans, and in studies reverse-translating these findings to animal models. Research in humans shows that adolescent cannabis use is widespread, and associated with defects in working memory, self-control and motivation. Similar results were obtained in animal studies, through which researchers were also able to test therapies that can reverse the effects of adolescent cannabis use in adulthood. These findings provide keys to prevent and treat the long term effect of adolescent cannabis use.

https://www.sciencedaily.com/releases/2019/05/190526135747.htm

How college students can end up in vicious cycle of substance abuse, poor academics, stress

April 16, 2019

Science Daily/Binghamton University

One negative behavior such as substance abuse or heavy alcohol drinking can lead college students toward a vicious cycle of poor lifestyle choices, lack of sleep, mental distress and low grades, according to new research from Binghamton University, State University of New York.

"We used a robust data-mining technique to identify associations between mental distress in college students with substance abuse, sleep, social behaviors, academic attitude and behaviors, and GPA (short-term and long-term as reflective of academic performance)," said Lina Begdache, assistant professor of Health and Wellness Studies at Binghamton University. "Positive behaviors such as abstinence from substance use, studious attitudes and responsibility toward work and family are reflective of a brain chemistry profile that supports mood and maturation of the prefrontal cortex of the brain. The latter matures last and supports impulse and emotional control as well as rationalization of thoughts.

"Interestingly, we identified potential cyclic behaviors that associate with severe mental distress that are linked to a change in brain chemistry that supports substance abuse, poor academic attitude and performance, poor sleep patterns, and neglect of family and work. The novelty of these findings is that we are proposing, based on the neuroscience of these behaviors, that one action may be leading to another until a vicious cycle sets in."

A total of 558 students from different U.S. colleges completed an anonymous survey on academic performance, daytime sleepiness, substance use and mental distress. Low mental distress in college students was associated with no substance abuse, responsible attitude toward learning as well as good academic efforts, high GPA (of above 3.0) and limited daytime sleepiness. Mild mental distress correlated with borderline work neglect and with a marginal negative association with grade-point average. Severe mental distress correlated with substance abuse (including excessive alcohol drinking), extreme daytime sleepiness, poor academic attitude and low GPA. This change in the direction of associations may reflect the neuroanatomical and neurochemical changes triggered by these factors that eventually contribute to mental distress. The results demonstrate that manageable lifestyle factors contribute to mental health in college students, which become potentially cyclic events that may impact academic performance.

"These factors that are associated with mental distress in college students are controllable factors, meaning that proper education of students may reduce risk of mental distress on college campuses, which is on the rise," said Begdache.

Begdache said that "it is important for young adults to recognize that one behavior may lead to a domino effect. For instance, using drugs recreationally, abusing alcohol or using "study" drugs not only affects brain chemistry but may affect diet and sleep, which may further alter brain function and brain maturity. Reduced brain maturity increases impulsivity, reduces emotional control and cognitive functions as well as GPA, eventually increasing mental distress with a potential long-lasting effect," said Begdache. "Brain maturity is a window of time and negative stimuli leave a permanent mark. Higher impulsivity and increased mental distress further support drug use, and a vicious cycle sets in. Luckily, we also identified a virtuous cycle; when young adults follow a healthy lifestyle (diet, sleep and exercise), they are more likely to avoid drugs and alcohol, which supports a normal brain maturity, which is then reflected in a higher GPA and responsible attitudes toward learning, work and family. These vicious or virtuous cycles have a long-lasting effect on brain function, so it is crucial that young adults are aware of the potential harm or benefits of their own actions."

Begdache and her team will next look into the effect of alcohol binging, gender differences in attitudes and mental distress.

"The rationale is that the brain morphology and connectivity between men and women is known to be different and that alcohol metabolism is also different between males and females," said Begdache.

https://www.sciencedaily.com/releases/2019/04/190416081419.htm

Performance-enhancing drugs may increase risk of teen cocaine abuse, impair fertility

Exposure to anabolic steroids increased psychoactive effects of cocaine in rat study

April 8, 2019

Science Daily/American Physiological Society

Performance-enhancing steroid use could increase the risk of cocaine use and addiction in teens, according to a new rodent study. The combination of these drugs could also impair fertility in young women. The research will be presented today at the American Physiological Society's (APS) annual meeting at Experimental Biology 2019 in Orlando, Fla.

Athletes sometimes use anabolic steroids to boost performance. In addition to building muscle, performance-enhancing drugs have been found to affect mood and behavior, including risk-taking behavior. Previous research has shown that approximately one-third of young adults who use anabolic steroids also use cocaine. This rate is substantially higher than the roughly 5 percent of young adults who use cocaine but do not take anabolic steroids. Although there appears to be a link between anabolic steroid use and the tendency to use other addiction-forming drugs in adults, it has not been well-studied in adolescents.

Researchers from the University of Puerto Rico studied female rats, half of which were exposed to nandrolone, one of the anabolic steroids most commonly used by young adults. After 10 days of steroid exposure, the animals were divided into four groups:

·      One group was exposed to nandrolone only.

·      One group was exposed to nandrolone and cocaine.

·      One group was exposed to cocaine only.

·      A control group was exposed to neither nandrolone nor cocaine.

The researchers observed that the group exposed to nandrolone showed increased sensitivity to cocaine -- called locomotor sensitization -- than the other groups. The researchers also saw a reduction in ovary weight and the development of ovarian cysts -- which can compromise fertility -- in the nandrolone groups. The animals exposed to cocaine alone did not show the same level of drug-induced locomotor sensitization.

Exposure to androgens during adolescence "modifies the brain circuitry that regulates addictive behaviors, increasing the psychoactive properties of cocaine," the researchers wrote. In addition, anabolic steroids are also detrimental to the female reproductive system and may reduce fertility. A similar outcome in humans could significantly increase the risk of cocaine addiction and negatively affect fertility in teen athletes who use performance-enhancing steroids.

https://www.sciencedaily.com/releases/2019/04/190408113944.htm

Children of incarcerated parents have more substance abuse, anxiety

August 23, 2019

Science Daily/Duke University

Children of incarcerated parents are six times more likely than other children to develop a substance use disorder as adults and nearly twice as likely to have diagnosable anxiety, according to new research from the Center for Child and Family Policy at the Duke University Sanford School of Public Policy.

In addition, children whose parents were incarcerated are more likely to encounter significant hurdles transitioning into adulthood, including being charged with a felony (35% vs. 11.5%), dropping out of high school (25.5% vs. 5.0%), becoming a teenage parent (14.3% vs. 2.8%), experiencing financial strain (37.2% vs. 17.5%), and being socially isolated (24.5% vs. 9.4%), the study found.

"The increased risk for adverse adult outcomes remained after accounting for childhood psychiatric status and other adversities, suggesting that parental incarceration is associated with profound and long-lasting effects for children," said co-author William E. Copeland of the University of Vermont, who conducted the research while at Duke. "This increased risk persisted whether the incarcerated parent was biologically related to the child or not. Risk for adverse adult outcomes increased further with each additional incarcerated parent figure."

The United States has among the highest incarceration rates in the world. The U.S. Department of Justice estimates that over half of those who are incarcerated are parents of children under age 18.

With more than 2.7 million children experiencing a parent being sent to jail or prison, understanding the long-term health and social implications of incarceration for children is critical, the researchers say.

The study was published Friday in JAMA Network Open. Lead author Beth Gifford of Duke University and Copeland, principal investigator for the Great Smoky Mountains Study, along with colleagues from Duke, the University of Vermont and the University of Zurich, analyzed data gathered between 1993 and 2015 on the life experiences of children from the Appalachian Mountains in western North Carolina from age nine until age 30.

Researchers considered all adults who had significant responsibility for the child's discipline or care to be "parental figures." They also interviewed families as many as eight times during childhood. Using those methods, researchers identified a higher prevalence of incarceration by parental figures (23.9 percent) than the 8 to 11 percent previously documented in other population-based studies.

Incarceration rates for parental figures were higher among racial and ethnic minorities: 47.9 percent among American Indians and 42.7 percent among African-Americans, compared with 21.4 percent among whites. Parental incarceration cases overwhelmingly involved fathers (87.9 percent).

"Our findings point to the potentially high societal costs of incarcerating children's caregivers -- potentially for generations to come," said Gifford. "From a public health perspective, preventing parental incarceration could improve the well-being of children and young adults, as could aiding children and families once a parent figure has been incarcerated."

https://www.sciencedaily.com/releases/2019/08/190823140734.htm

Cannabis-based medicine may reduce seizures for children with difficult-to-treat epilepsy

April 30, 2019

Science Daily/American Academy of Neurology

Taking a pharmaceutical formulation of cannabidiol, a cannabis-based medicine, cut seizures nearly in half for children with a rare and severe type of epilepsy called Dravet syndrome, according to a phase 3 study released today that will be presented at the American Academy of Neurology's 71st Annual Meeting in Philadelphia, May 4 to 10, 2019. Dravet syndrome, which starts in infancy, can lead to intellectual disability and frequent, prolonged seizures. Cannabidiol is derived from marijuana that does not include the psychoactive part of the plant that creates a "high."

"It's exciting to be able to offer another alternative for children with this debilitating form of epilepsy and their families," said study author Ian Miller, MD, of Nicklaus Children's Hospital, formerly Miami Children's Hospital, in Florida. "The children in this study had already tried an average of four epilepsy drugs with no success and at the time were taking an average of three additional drugs, so to have this measure of success with cannabidiol is a major victory."

The study involved 199 children with an average age of 9 who were divided into three groups. One group received 20 milligrams per kilogram (mg/kg) per day of cannabidiol, the second group received 10 mg/kg per day and the third group received a placebo.

Seizures were recorded for four weeks before the treatments were started to establish a baseline. Then the participants received the treatment for 14 weeks. By the end of the study, seizures with convulsions had decreased for those taking the high dose of the drug by 46 percent and by 49 percent for those taking the lower dose of the drug, compared to 27 percent for those taking the placebo.

Total seizures reduced by 47 percent for those in the high dose group, by 56 percent for those in the lower dose group and by 30 percent for those in the placebo group. In the high dose group, 49 percent of the participants had their seizures cut in half or more, compared to 44 percent in the low dose group and 26 percent in the placebo group.

All of the groups reported side effects, with 90 percent of the high dose group, 88 percent of the low dose group and 89 percent of the placebo group. The most common side effects were decreased appetite, diarrhea, sleepiness, fever and fatigue. About 25 percent of those in the high dose group had serious side effects, compared to 20 percent of those in the low dose group and 15 percent of those in the placebo group. Only participants in the high dose group stopped taking the drug due to side effects; that number was 7 percent.

"Based on these results, dose increases above 10 mg/kg per day should be carefully considered based on the effectiveness and safety for each individual," Miller said.

https://www.sciencedaily.com/releases/2019/04/190430164219.htm

Marijuana for morning sickness? It's not great for baby's brain

Study pinpoints how pot exposure during pregnancy can lead to problems with behavior and memory

April 9, 2019

Science Daily/Experimental Biology

With a growing number of states legalizing recreational or medical marijuana, more women are using the drug during pregnancy, in part due to its reported ability to relieve morning sickness. A new study, conducted in rats, sheds light on how cannabis exposure affects the brain of a developing fetus.

Previous research has shown children born to mothers who used marijuana during pregnancy are more likely to develop behavioral problems as well as learning and memory impairments. The new research offers further confirmation on those findings and pinpoints how the drug alters the intricate connections in nerves in the hippocampus, the brain's center for learning and memory. Understanding exactly how marijuana affects these brain connections could one day lead to interventions to reduce the damage, researchers say.

"The findings from this study will serve as an excellent premise for future interventions to restore memory in children exposed to cannabis during pregnancy, and for the first time, identify a specific mechanism by which learning and memory impairment occurs and how this impairment can be ameliorated," said Priyanka Das Pinky, a graduate student in the laboratory of Vishnu Suppiramaniam, PhD, acting associate dean for research and graduate programs at Auburn University.

Pinky will present the research at the American Society for Pharmacology and Experimental Therapeutics annual meeting during the 2019 Experimental Biology meeting, held April 6-9 in Orlando, Fla.

According to one previous analysis, the use of marijuana during pregnancy increased by 62 percent between 2002 and 2014, paralleling the rising popularity of marijuana in the adult U.S. population as a whole.

"Based on our research and the previous existing findings in the field, it can be said that using marijuana during pregnancy would not be a wise choice," said Pinky. "However, it is also notable that the observed effect in the offspring can vary according to their age and according to the trimester during which they were exposed to the drug as well as dose and route of administration of the drug."

The research team raised several groups of rats and exposed some of the females to a synthetic chemical that activates the same proteins as cannabis while they were pregnant. They used a dose equivalent to moderate-to-heavy marijuana use in humans. Examining the brains of the baby rats, they found the connections, or synapses, between the nerves in the hippocampus were reduced in those exposed to the synthetic cannabis.

Upon further examination, they found evidence that the root of the problem was a reduction in neural cell adhesion molecules (NCAM), a protein important for maintaining proper neural connection and synaptic strength. The finding suggests it may be possible to counteract marijuana's effects by increasing the NCAM, though more research is needed to understand the mechanisms involved and determine whether the findings, from studies in animals, would translate to human babies.

"It is still very early to come up with a conclusion about the possible safe use of marijuana during pregnancy," Pinky said. "More research is needed to evaluate the exact mechanism by which NCAM and/or its active form is modulating cellular effects while focusing on target specific drug development for amelioration of the observed cognitive deficits."

https://www.sciencedaily.com/releases/2019/04/190409135933.htm

Performance-enhancing drugs may increase risk of teen cocaine abuse, impair fertility

Exposure to anabolic steroids increased psychoactive effects of cocaine in rat study

April 8, 2019

Science Daily/American Physiological Society

Performance-enhancing steroid use could increase the risk of cocaine use and addiction in teens, according to a new rodent study. The combination of these drugs could also impair fertility in young women. The research will be presented today at the American Physiological Society's (APS) annual meeting at Experimental Biology 2019 in Orlando, Fla.

Athletes sometimes use anabolic steroids to boost performance. In addition to building muscle, performance-enhancing drugs have been found to affect mood and behavior, including risk-taking behavior. Previous research has shown that approximately one-third of young adults who use anabolic steroids also use cocaine. This rate is substantially higher than the roughly 5 percent of young adults who use cocaine but do not take anabolic steroids. Although there appears to be a link between anabolic steroid use and the tendency to use other addiction-forming drugs in adults, it has not been well-studied in adolescents.

Researchers from the University of Puerto Rico studied female rats, half of which were exposed to nandrolone, one of the anabolic steroids most commonly used by young adults. After 10 days of steroid exposure, the animals were divided into four groups:

·     One group was exposed to nandrolone only.

·     One group was exposed to nandrolone and cocaine.

·     One group was exposed to cocaine only.

·     A control group was exposed to neither nandrolone nor cocaine.

The researchers observed that the group exposed to nandrolone showed increased sensitivity to cocaine -- called locomotor sensitization -- than the other groups. The researchers also saw a reduction in ovary weight and the development of ovarian cysts -- which can compromise fertility -- in the nandrolone groups. The animals exposed to cocaine alone did not show the same level of drug-induced locomotor sensitization.

Exposure to androgens during adolescence "modifies the brain circuitry that regulates addictive behaviors, increasing the psychoactive properties of cocaine," the researchers wrote. In addition, anabolic steroids are also detrimental to the female reproductive system and may reduce fertility. A similar outcome in humans could significantly increase the risk of cocaine addiction and negatively affect fertility in teen athletes who use performance-enhancing steroids.

https://www.sciencedaily.com/releases/2019/04/190408113944.htm

Psychostimulants play a major role in fatal strokes among young adults

April 3, 2019

Science Daily/Wiley

An estimated 76 million people use psychostimulants, which include illicit drugs such as methamphetamine, cocaine, and 3,4-methylenedioxymethamphetamine, as well as prescription stimulants. A new Journal of Forensic Sciences study from Australia is the first to present national data of psychostimulant use in young adults who experienced a fatal stroke.

Investigators found that from 2009-2016, psychostimulant users constituted nearly a fifth of the 279 cases of fatal stroke in adults aged 15-44 years, the majority of which had evidence of consumption immediately prior to the fatal stroke.

Methamphetamine was overwhelmingly the drug implicated. The median methamphetamine concentration was similar to that reported for all methamphetamine-related deaths in Australia but less than half that of deaths attributed solely to methamphetamine toxicity. This suggests that high concentrations are not essential to cause a methamphetamine-related stroke.

Cases of haemorrhagic stroke were also documented involving other illicit and licit psychostimulants. In no cases were medications for attention deficit hyperactivity disorder identified.

"This is the first study to show the major role that psychostimulants play in causing fatal strokes amongst young adults," said lead author Prof. Shane Darke, of the University of New South Wales, in Australia. "All of these deaths were preventable. Users of these drugs, however, appear to be largely unaware of the risk. Psychostimulant users, and those treating them, need to be aware of their elevated stroke risk, which may have devastating consequences.

https://www.sciencedaily.com/releases/2019/04/190403080504.htm

Brain growth inhibited by heavy alcohol use

April 1, 2019

Science Daily/Oregon Health & Science University

New research in nonhuman primates shows that heavy use of alcohol can actually slow the rate of growth in developing brains. The study, to be published April 1, in the journal eNeuro, shows that heavy alcohol use reduced the rate of brain growth by 0.25 milliliters per year for every gram of alcohol consumed per kilogram of body weight. In human terms, that's the equivalent of four beers per day.

Heavy use of alcohol among adolescents and young adults is not only dangerous in its own right, but new research in nonhuman primates shows that it can actually slow the rate of growth in developing brains.

The study, published today in the journal eNeuro, shows that heavy alcohol use reduced the rate of brain growth by 0.25 milliliters per year for every gram of alcohol consumed per kilogram of body weight. In human terms, that's the equivalent of four beers per day. The research involved rhesus macaque monkeys at the Oregon National Primate Research Center.

"Chronic alcohol self-intoxication reduced the growth rate of brain, cerebral white matter and subcortical thalamus," the researchers write.

Researchers measured brain growth through magnetic resonance imaging of 71 rhesus macaques that voluntarily consumed ethanol or beverage alcohol. Scientists precisely measured intake, diet, daily schedules and health care, thus ruling out other factors that tend to confound results in observational studies involving people. The findings in the study help validate previous research examining the effect of alcohol use on brain development in people.

"Human studies are based on self-reporting of underage drinkers," said co-author Christopher Kroenke, Ph.D., an associate professor in the Division of Neuroscience at the primate center. "Our measures pinpoint alcohol drinking with the impaired brain growth."

The new study is the first to characterize normal brain growth of 1 milliliter per 1.87 years in rhesus macaques in late adolescence and early adulthood. And it further reveals a decrease in the volume of distinct brain areas due to voluntary consumption of ethanol.

Lead author Tatiana Shnitko, Ph.D., a research assistant professor in the Division of Neuroscience at the primate center, said previous research has shown the brain has a capacity to recover at least in part following the cessation of alcohol intake. However, it's not clear whether there would be long-term effects on mental functions as the adolescent and young adult brain ends its growth phase. The next stage of research will explore that question.

"This is the age range when the brain is being fine-tuned to fit adult responsibilities," Shnitko said. "The question is, does alcohol exposure during this age range alter the lifetime learning ability of individuals?"

This study was funded by the National Institute on Alcohol Abuse and Alcoholism (U01 AA013510, P60 AA013510 and U24 AA025473.

https://www.sciencedaily.com/releases/2019/04/190401133019.htm

Surge in cannabis use among youth preceded legalization in Canada

March 25, 2019

Science Daily/University of Waterloo

National discussions on cannabis legalization, along with increased access to medical marijuana, may have encouraged more high school students to consume the drug years before it became legal in Canada.

A recent study using data from more than 230,000 questionnaires by Canadian high school students in grades 9 to 12 found that almost 10 per cent reported having used the drug at least once per week in 2017-18, with a further 18 per cent saying they had used it at least once in the last year.

Both weekly and occasional use reached their lowest points in 2014-15 (9 percent and 15 percent respectively) and have since been rising steadily.

"The problem was developing while legalization was being discussed, but well before concrete steps to change the law were taken," said lead author Alex Zuckermann, a post-doctoral fellow with the Public Health Agency of Canada working in the School of Public Health and Health Systems.

"With medicinal use more widespread and talk of total legalization starting, we saw a shift in public perception starting around 2014. Before that, youth cannabis use was declining. These changing social norms may have contributed to rising youth use."

The work used data from the COMPASS Study, an annual survey of high school students in grades 9 to 12 in Ontario and Alberta. The demographic groups that saw the biggest increases since 2014-15 were female and Indigenous youth. Weekly use for females went from 7 to 8 percent, and occasional use from 17 to 19 percent during this time period. Indigenous youth weekly use went from 23 to 25 percent, and occasional use from 18 to 21 percent.

"We often think of male youth when we talk about drug use, but here female students are driving increases. Historically, their use has been more stigmatized, so normalization may be having a bigger effect," said Zuckermann. "We also see that Indigenous youth start young and have by far the highest rates of current use, factors that will have long-term health implications and need to be addressed."

In 2017-18, rates of lifetime and past-year cannabis use were highest among male (33 and 29 percent) and Indigenous students (55 and 46 percent), and lowest among Asian students (17 and 14 percent). Female students stood at 31 percent for lifetime use and 26 percent in the past year.

"The ability to track multiple risk factors among youth over time and maintain ongoing data systems like COMPASS can provide valuable information to policymakers," added Scott Leatherdale, principal investigator and a professor in the School of Public Health and Health Systems. "It helps to provide the necessary evidence to learn from new policy implementation."

https://www.sciencedaily.com/releases/2019/03/190325120358.htm

Is anxiety in childhood and adolescence linked to later alcohol use disorders?

March 20, 2019

Science Daily/Wiley

In an Addiction analysis of relevant published studies, investigators found some evidence for a positive association between anxiety during childhood and adolescence with later alcohol use disorders.

Approximately 43 percent of associations were positive, meaning that anxiety was associated with a higher likelihood of later alcohol use disorders; however, 11 percent of associations were negative, with anxiety being associated with a lower likelihood of later alcohol use disorders. Approximately 30 percent of associations were equivocal and 15 percent were unclassifiable based on the information reported.

The authors of the analysis noted that it is important to establish which anxious individuals consume more alcohol and develop alcohol use disorders in order to develop targeted interventions.

"The evidence from prospective cohort studies is suggestive but not conclusive of a positive association between anxiety during childhood and adolescence and subsequent alcohol use disorder," said lead author Maddy Dyer, of the University of Bristol, in the UK. "Associations of anxiety with later drinking frequency or quantity and binge drinking were inconsistent. Further research is needed to understand why there are differences in associations for consumption levels versus problematic use, and to determine which individuals with anxiety develop alcohol problems."

https://www.sciencedaily.com/releases/2019/03/190320102030.htm

No evidence tougher policies deter adolescent cannabis use

February 19, 2019

Science Daily/University of Kent

A new study has found no evidence that teenage cannabis use is lower in countries with tougher

The study, by Alex Stevens, Professor in Criminal Justice in Kent's School for Social Policy, Sociology and Social Research, used data from the World Health Organisation's Health Behaviour in School-aged Children survey. This survey asked over 100,000 teenagers in 38 countries, including the UK, USA, Russia, France, Germany and Canada, about their cannabis use.

Professor Stevens's analysis of the data found no association between a country having a more liberal policy on cannabis use and higher rates of teenage cannabis use. The analysis controlled for differences between the countries, including their national income, and between the teenagers, including their gender, their affluence and psychological problems.

The new study was undertaken in response to a 2015 study that had concluded there was an association between policy liberalisation and a higher likelihood of adolescent cannabis use. This study has been used in the past to justify calls for tougher policies for cannabis use.

However, Professor Stevens found this was based on a misinterpretation of that study's own numerical results. When taking into account the differences in cannabis use between boys and girls in different countries, and using more of the available data, a statistically significant association between policy liberalisation and adolescent cannabis use cannot be found.

Professor Stevens said: 'My new study joins several others which show no evidence of a link between tougher penalties and lower cannabis use. This is useful information for governments as they consider the best way to deal with cannabis. As it is, the harms and costs of imposing criminal convictions on people who use cannabis do not seem to be justified by an effect in reducing cannabis use.'

https://www.sciencedaily.com/releases/2019/02/190219111730.htm

Parents: Keep medical marijuana dispensaries away from kids

About 3/4 of parents say dispensaries should not be near schools

February 18, 2019

Science Daily/Michigan Medicine - University of Michigan

Seven in 10 parents think they should have a say in whether dispensaries are located near their child's school or daycare and most say they should be banned within a certain distance of those facilities.

With medical marijuana now legal in about two-thirds of U.S. states, there's growing concern about how dispensaries may impact surrounding neighborhoods and communities.

And parents in a new national poll overwhelmingly agree on one place dispensaries should not be allowed: anywhere near children.

Seven in 10 parents think they should have a say in whether dispensaries are located near their child's school or daycare and most say they should be banned within a certain distance of those facilities, according to the C.S. Mott Children's Hospital National Poll on Children's Health at the University of Michigan.

Highest on the list of concerns was the risk impaired drivers may pose to children -- with nearly half of parents saying this was a significant worry. A recent study found that more than half of people taking cannabis for chronic pain report driving while high.

"Medical marijuana has become legal in the majority of states but there is wide variation in state and local policies that regulate the location and operation of dispensaries," says poll co-director Sarah Clark, M.P.H.

"The majority of parents feel strongly that they should give local input on decisions regarding where dispensaries may open and also support limitations on how close dispensaries could be to children's areas."

Aside from the top concern involving drivers under the influence, some parents also worried about the possibility of a child finding and ingesting edible marijuana inadvertently left behind by a dispensary customer (48 percent), and teens having easier opportunities accessing marijuana (49 percent.) Other dispensary concerns included setting a bad example for kids (45 percent) and bringing violent crime to the area (35 percent).

Three quarters of parents indicated general support for legal medical marijuana, including one third of parents who support the option for children. Just 26 percent of parents opposed medical marijuana.

At the same time, most parents agreed that dispensaries should be banned within a certain distance of elementary schools, middle and high schools, and daycare centers. Forty-four percent of parents also believed dispensaries should not be close to places of worship. Support for such bans was equally strong among both mothers and fathers, younger and older parents, and parents of higher and lower income.

"Most parents seem to understand that marijuana can have legitimate medical benefits, but parents also have major concerns about the risks that medical marijuana dispensaries might pose to children," Clark says. "When it comes to where dispensaries are located, many parents feel that any area near children is too close for comfort."

Most parents (77 percent) agreed that medical marijuana dispensaries should have the same regulations as liquor stores for where they can be located. Meanwhile, 52 percent of parents said dispensaries should have the same rights as other businesses. Nearly all parents (90 percent) felt dispensaries should undergo inspections to ensure they are following all regulations.

Nearly half of parents (45 percent) said that medical marijuana is legal in their state, and 24 percent knew there was at least one medical marijuana dispensary in their community. Only 20 percent reported that their state or community has regulations about where dispensaries can be located, while 59 percent did not know if such regulations exist.

While most parents wanted to be consulted about locating a dispensary near their child's school or daycare, this may prove difficult, Clark says. There is no consistent state or local framework to regulate the location and operations of dispensaries. Some states may have added legal complexities differentiating the sale of medical versus recreational marijuana.

It may also be confusing about whether parents need to contact elected officials or commissions, and if they should focus on the state or local level when an application is filed for a new dispensary. Decisions about the location of new dispensaries could be made through a state law, a local zoning regulation, or other action.

"Parents who want to share their views about dispensaries before any open in their school's neighborhood may have limited opportunities to do so. They may not even be aware that a specific dispensary location is under consideration until the decision has already been made," Clark says.

"The lack of established standards may lead officials to enact policies that may not address parents' concerns," Clark adds. "Parents who want to provide input about local dispensaries may need to take the initiative to learn about the rules for opening a dispensary in their community and what steps they should follow to be involved in these decisions."

https://www.sciencedaily.com/releases/2019/02/190218094005.htm

Teens living in US states allowing medical marijuana smoke less cannabis

February 14, 2019

Science Daily/Taylor & Francis Group

According to a large-scale study of American high school students, legalizing medicinal marijuana has actually led to a drop in cannabis use among teenagers. The study used the results of an anonymous survey given to more than 800,000 high school students across 45 states to calculate the number of teens who smoke cannabis.

The study, published today in the American Journal of Drug and Alcohol Abuse used the results of an anonymous survey given to more than 800,000 high school students across 45 states to calculate the number of teens who smoke cannabis.

It found that the number of teenage cannabis smokers was 1.1% less in states that had enacted medical marijuana laws (MML) compared to those that hadn't, even when accounting for other important variables such as tobacco and alcohol policies, economic trends, youth characteristics and state demographics.

"We found that for every group of 100 adolescents, one fewer will be a current user of marijuana following the enactment of medical marijuana laws," says Dr Rebekah Levine Coley, a Professor of psychology at Boston College, who led the study.

"When we looked at particular subgroups of adolescents, this reduction became even more pronounced. For example 3.9% less Black and 2.7% less Hispanic youths now use marijuana in states with MML."

As the survey was administered over a period of 16 years, the researchers were able to compare the changes in teenager's marijuana use in states that adopted MML with those that hadn't, allowing them to more precisely pinpoint the effects of the legislation. Intriguingly, the study found that the longer the laws had been in place, the greater the reduction in teen marijuana use.

The results shine a light on an important debate taking place in America about the relative benefits and risks of decriminalizing marijuana.

"Some people have argued that decriminalizing or legalizing medical marijuana could increase cannabis use amongst young people, either by making it easier for them to access, or by making it seem less harmful." says Dr Rebekah Levine Coley.

"However, we saw the opposite effect. We were not able to determine why this is, but other research has suggested that after the enactment of medical marijuana laws, youths' perceptions of the potential harm of marijuana use actually increased. Alternatively, another theory is that as marijuana laws are becoming more lenient, parents may be increasing their supervision of their children, or changing how they talk to them about drug use."

Importantly the study found that unlike medical marijuana laws, decriminalizing recreational marijuana had no noticeable effect on adolescents' cannabis use, except for a small decline in marijuana smoking among 14-year olds and people from Hispanic backgrounds, and an increase in use among white adolescents. Neither policies had any effect on frequent or heavy users of marijuana, suggesting that these students are not easily influenced by stat

e laws.

https://www.sciencedaily.com/releases/2019/02/190214191934.htm