College students use more marijuana in states where it's legal, but they binge drink less
January 13, 2020
Science Daily/Oregon State University
Marijuana use among college students has been trending upward for years, but in states that have legalized recreational marijuana, use has jumped even higher.
An Oregon State University study published today in Addiction shows that in states where marijuana was legalized by 2018, both occasional and frequent use among college students has continued to rise beyond the first year of legalization, suggesting an ongoing trend rather than a brief period of experimentation.
Overall, students in states with legal marijuana were 18% more likely to have used marijuana in the past 30 days than students in states that had not legalized the drug. They were also 17% more likely to have engaged in frequent use, defined as using marijuana on at least 20 of the past 30 days.
The differences between states with and without legalization escalated over time: Six years after legalization in early-adopting states, students were 46% more likely to have used marijuana than their peers in non-legalized states.
Between 2012 and 2018, overall usage rates increased from 14% to 17% in non-legalized states, but shot up from 21% to 34% in the earliest states to legalize the drug. Similar trends appeared in states that legalized marijuana more recently.
Conducted by Harold Bae from OSU's College of Public Health and Human Sciences and David Kerr from OSU's College of Liberal Arts, this is the first study of college students to look broadly at multiple states that have legalized recreational marijuana and to go beyond the first year following legalization.
It includes data from seven states and 135 colleges where marijuana was legalized by 2018 and from 41 states and 454 colleges where recreational use was not legal.
That scope allowed Bae and Kerr to examine trends in the earliest adopting states as well as more recent adopters -- though, the data for the study is stripped of state- and college-identifying information, so does not speak specifically to any one state or institution.
The data comes from the National College Health Assessment survey from 2008 to 2018, which asks about a wide range of health behaviors including drug and alcohol use and is administered anonymously to encourage students to respond more honestly. More than 850,000 students participated.
Looking at specific demographics, researchers found that the effect was stronger among older students ages 21-26 than minors ages 18-20; older students were 23% more likely to report having used marijuana than their peers in non-legalized states. The effect was also stronger among female students and among students living in off-campus housing, possibly because universities adhere to federal drug laws that still classify marijuana as an illegal substance.
"It's easy to look at the findings and think, 'Yeah, of course rates would increase,'" Kerr said. "But we need to quantify the effects these policy changes are having."
Furthermore, he said, researchers are not finding increases in adolescents' marijuana use following legalization. "So it is surprising and important that these young adults are sensitive to this law. And it's not explained by legal age, because minors changed too."
A recent companion study published in Addictive Behaviors in November by OSU doctoral candidate Zoe Alley along with Kerr and Bae examined the relationship between recreational marijuana legalization and college students' use of other substances.
Using the same dataset, they found that after legalization, students ages 21 and older showed a greater drop in binge drinking than their peers in states where marijuana was not legal. Binge drinking was defined as having five or more drinks in a single sitting within the previous two weeks.
Researchers have not yet tested any hypotheses as to why binge drinking fell, but they have some ideas.
An outside study previously found that illegal marijuana use decreases sharply when people hit 21 -- where there is a sharp increase in alcohol use.
"When you're under 21, all substances are equally illegal," Alley said. "In most states, once you reach 21, a barrier that was in the way of using alcohol is gone, while it's intact for marijuana use. But when marijuana is legal, this dynamic is changed."
Binge drinking has been on the decline among college students in recent years, but dropped more in states that legalized marijuana than in states that did not.
"So in these two studies we saw changes after legalization that really differed by substance," Kerr said. "For marijuana we saw state-specific increases that went beyond the nationwide increases, whereas binge drinking was the opposite: a greater decrease in the context of nationwide decreases."
The magnitude of effect was much larger with marijuana than with any of the other substances, Bae added. "So the changes following recreational marijuana legalization were quite specific to cannabis use."
Future research is needed to see how those trends hold up over time, as additional states legalize marijuana and existing states continue to tweak their current policies, the researchers said.
https://www.sciencedaily.com/releases/2020/01/200113131637.htm
The dangers of teens using marijuana
September 25, 2014
Science Daily/Loyola University Health System
Whether states should legalize marijuana for recreational and medical use is a hot topic across the country. As the debates continue a potentially dangerous environment is being created where more preteens, teens and young adult are beginning to use the substance with the feeling that it is safe. In fact, 36 percent of all seniors in high school and 7 percent of eighth-graders report using the drug in the past month, according to a recent study. Though public perception is that marijuana is a harmless drug, research is showing it can have a damaging impact on developing brains and may lead to life-long addiction.
"Teens are seeing marijuana as a safe substance, but its effects on the adolescent brain can be dangerous, especially if there is heavy use. As the stigma of marijuana use becomes less the number of teens using the drug has increased. More high-schoolers in the U.S. now smoke marijuana than they do cigarettes," said Garry Sigman, MD, director of the adolescent medicine division at Loyola University Health System and professor in the Department of Pediatrics at Loyola University Chicago Stritch School of Medicine.
Marijuana is an addictive substance and, according to Sigman, adolescents are 2-4 times more likely to become dependent on the drug within two years after first use compared with adult users.
"Marijuana is the most common substance addiction being treated in adolescents in rehabilitation centers across the country. Like all addictive substances, marijuana is used to lessen uncomfortable feelings like anxiety and depression. Because the type of addiction is seen as less 'intense' in comparison to other substances such as cocaine or heroin, many people don't realize that marijuana can cause dependence and has a withdrawal syndrome," Sigman said.
Some adolescents use marijuana only occasionally because of peer pressure at a party or in a social setting, but others self-medicate with marijuana to cope with emotions and stress. One of the signs of a substance-use disorder is when drugs are used often to cope with uncomfortable feelings.
Addiction isn't the only hazard for adolescents when it comes to smoking marijuana. Research shows that heavy use can lead to neurotoxicity and alternations in brain development leading to: • Impairment in thinking • Poor educational outcomes and perhaps a lower IQ • Increased likelihood of dropping out of school • Symptoms of chronic bronchitis • Increased risk of psychosis disorders in those who are predisposed.
"Parents should inform themselves about the scientific facts relating to marijuana and the developing brain and be able to discuss the topic calmly and rationally. They need to explain that the dose of the drug in a 'joint' is three to four times higher than in years past, and that if the parents occasionally used during their lives, they now know that the risk is present if used before adulthood," Sigman said.
https://www.sciencedaily.com/releases/2014/09/140925150606.htm
Heavy Marijuana Use May Damage Developing Brain in Teens, Young Adults
February 3, 2009
Science Daily/Children's Hospital of Philadelphia
Adolescents and young adults who are heavy users of marijuana are more likely than non-users to have disrupted brain development, according to a new study. Pediatric researchers found abnormalities in areas of the brain that interconnect brain regions involved in memory, attention, decision-making, language and executive functioning skills. The findings are of particular concern because adolescence is a crucial period for brain development and maturation.
The researchers caution that the study is preliminary and does not demonstrate that marijuana use causes the brain abnormalities. However, "Studies of normal brain development reveal critical areas of the brain that develop during late adolescence, and our study shows that heavy cannabis use is associated with damage in those brain regions," said study leader Manzar Ashtari, Ph.D., director of the Diffusion Image Analysis and Brain Morphometry Laboratory in the Radiology Department of The Children's Hospital of Philadelphia.
The study appeared early last month in the Journal of Psychiatric Research. The current research builds on previous work by Ashtari and colleagues, who used the same imaging technology to analyze normal brain development in adolescent subjects.
In the current study, working with child psychiatrist Sanjiv Kumra, M.D., now at the University of Minnesota, Ashtari and colleagues performed imaging studies on 14 young men from a residential drug treatment center in New York State, as well as 14 age-matched healthy controls. All the study subjects were males, with an average age of 19. The researchers performed the imaging studies at Long Island Jewish Medical Center.
The 14 subjects from the drug treatment center all had a history of heavy cannabis use during adolescence. On average, they had smoked marijuana from age 13 till age 18 or 19, and reported smoking nearly 6 marijuana joints daily in the final year before they stopped using the drug.
The study team performed a type of magnetic resonance imaging scan called diffusion tensor imaging (DTI) that measures water movement through brain tissues. "The abnormal patterns of water diffusion that we found among the young men with histories of marijuana use suggest damage or an arrest in development of the myelin sheath that surrounds brain cells," said Ashtari. Myelin provides a coating around brain cells similar to insulation covering an electrical wire. If myelin does not function properly, signaling within the brain may be slower.
Myelin gives its color to the white matter of the brain, and covers the nerve fibers that connect different brain regions. "Our results suggest that early-onset substance use may alter the development of white matter circuits, especially those connections among the frontal, parietal and temporal regions of the brain," said Ashtari. "Abnormal white matter development could slow information transfer in the brain and affect cognitive functions."
Ashtari added that the findings are preliminary. Among other limitations of the study, such as a small sample size, five of the 14 subjects with heavy cannabis use also had a history of alcohol abuse, which may have contributed an effect. Also, it is possible that the brain abnormalities may have predisposed the subjects to drug dependence, rather than drug usage causing the brain abnormalities.
"Further research should be done to investigate the relation between repeated marijuana use and white matter development," said Ashtari. "However, our work reinforces the idea that the adolescent brain may be especially vulnerable to risky behaviors such as substance abuse, because of crucial neural development that occurs during those years."
The National Institute of Mental Health provided grant support for this research. Ashtari's and Kumra's co-authors were Kelly Cervellione, of Jamaica Hospital Medical Center, Jamaica, N.Y.; John Cottone, of Zucker Hillside Hospital, Glen Oaks, N.Y.; and Babak A. Ardekani, of The Nathan Kline Institute for Psychiatric Research, Orangeburg, N.Y. Serge Sevy of Zucker Hillside Hospital also contributed to the project.
https://www.sciencedaily.com/releases/2009/02/090202175105.htm
Cannabis use in teens linked to risk of depression in young adults
Cannabis use among adolescents is found to be associated with increased risk of depression and anxiety in adulthood
February 13, 2019
Science Daily/University of Oxford
Cannabis is the most commonly used recreational drug by teenagers worldwide. In Canada, among youth aged 15 to 19 years, the rate of past-year cannabis use is 20.6 percent, while in England, 4 percent of adolescents aged 11 to 15 years used cannabis in the last month.
While there has been a lot of focus on the role of cannabis use in psychosis, there has been less attention on whether cannabis use is associated with an increased risk of common mental health disorders, such as depression and anxiety.
Researchers from McGill University and the University of Oxford carried out a systematic review and meta-analysis of the best existing evidence and analysed 23,317 individuals (from 11 international studies) to see whether use of cannabis in young people is associated with depression, anxiety and suicidality in early adulthood.
They found that cannabis use among adolescents is associated with a significant increased risk of depression and suicidality in adulthood (not anxiety). While the individual-level risk was found to be modest, the widespread use of the drug by young people makes the scale of the risk much more serious.
The population attributable risk was found to be around 7%, which translates to more than 400,000 adolescent cases of depression potentially attributable to cannabis exposure in the US, 25,000 in Canada and about 60,000 in the UK.
Dr. Gabriella Gobbi, Professor, Department of Psychiatry, McGill University and a scientist at the Research Institute of the McGill University Health Centre, states: "While the link between cannabis and mood regulation has been largely studied in preclinical studies, there was still a gap in clinical studies regarding the systematic evaluation of the link between adolescent cannabis consumption and the risk of depression and suicidal behaviour in young adulthood. This study aimed to fill this gap, helping mental health professionals and parents to better address this problem."
Professor Andrea Cipriani, NIHR Research Professor of Psychiatry at the University of Oxford, said: 'We looked at the effects of cannabis because its use among young people is so common, but the long-term effects are still poorly understood. We carefully selected the best studies carried out since 1993 and included only the methodologically sound ones to rule out important confounding factors, such us premorbid depression.'
'Our findings about depression and suicidality are very relevant for clinical practice and public health. Although the size of the negative effects of cannabis can vary between individual adolescents and it is not possible to predict the exact risk for each teenager, the widespread use of cannabis among the young generations makes it an important public health issue.
'Regular use during adolescence is associated with lower achievement at school, addiction, psychosis and neuropsychological decline, increased risk of motor vehicle crashes, as well as the respiratory problems that are associated with smoking.'
The active ingredient in cannabis,THC, mediates most of psychoactive and mood-related effects of cannabis and also has addictive properties. Preclinical studies in laboratory animals reported an association between pubertal exposure to cannabinoids and adult-onset depressive symptoms. It is thought that cannabis may alter the physiological neurodevelopment (frontal cortex and limbic system) of adolescent brains.
While the review of observational studies was the first to look at the effects of cannabis use in adolescents only, it was not possible to predict the risk at the individual level, nor was it possible to discern information about the dose-dependent risk of cannabis use.
https://www.sciencedaily.com/releases/2019/02/190213172307.htm
Reversing the negative effects of adolescent marijuana use
September 12, 2017
Science Daily/University of Western Ontario
Researchers at Western University have found a way to use pharmaceuticals to reverse the negative psychiatric effects of THC, the psychoactive chemical found in marijuana. Chronic adolescent marijuana use has previously been linked to the development of psychiatric diseases, such as schizophrenia, in adulthood. But until now, researchers were unsure of what exactly was happening in the brain to cause this to occur.
"What is important about this study is that not only have we identified a specific mechanism in the prefrontal cortex for some of the mental health risks associated with adolescent marijuana use, but we have also identified a mechanism to reverse those risks," said Steven Laviolette, professor at Western's Schulich School of Medicine & Dentistry.
In a study published online today in Scientific Reports the researchers demonstrate that adolescent THC exposure modulates the activity of a neurotransmitter called GABA in the prefrontal cortex region of the brain. The team, led by Laviolette and post-doctoral fellow Justine Renard, looked specifically at GABA because of its previously shown clinical association with schizophrenia.
"GABA is an inhibitory neurotransmitter and plays a crucial role in regulating the excitatory activity in the frontal cortex, so if you have less GABA, your neuronal systems become hyperactive leading to behavioural changes consistent with schizophrenia," said Renard.
The study showed that the reduction of GABA as a result of THC exposure in adolescence caused the neurons in adulthood to not only be hyperactive in this part of the brain, but also to be out of synch with each other, demonstrated by abnormal oscillations called 'gamma' waves. This loss of GABA in the cortex caused a corresponding hyperactive state in the brain's dopamine system, which is commonly observed in schizophrenia.
By using drugs to activate GABA in a rat model of schizophrenia, the team was able to reverse the neuronal and behavioural effects of the THC and eliminate the schizophrenia-like symptoms.
Laviolette says this finding is especially important given the impending legalization of marijuana in Canada. "What this could mean is that if you are going to be using marijuana, in a recreational or medicinal way, you can potentially combine it with compounds that boost GABA to block the negative effects of THC."
The research team says the next steps will examine how combinations of cannabinoid chemicals with compounds that can boost the brains GABA system may serve as more effective and safer treatments for a variety of mental health disorders, such as addiction, depression and anxiety.
https://www.sciencedaily.com/releases/2017/09/170912134809.htm
Marijuana and vulnerability to psychosis
July 5, 2017
Science Daily/University of Montreal
The link between marijuana use and psychotic-like experiences has been confirmed in a Canadian adolescent cohort.
Going from an occasional user of marijuana to a weekly or daily user increases an adolescent's risk of having recurrent psychotic-like experiences by 159%, according to a new Canadian study published in the Journal of Child Psychology and Psychiatry. The study also reports effects of marijuana use on cognitive development and shows that the link between marijuana use and psychotic-like experiences is best explained by emerging symptoms of depression.
"To clearly understand the impact of these results, it is essential to first define what psychotic-like experiences are: namely, experiences of perceptual aberration, ideas with unusual content and feelings of persecution," said the study's lead author, Josiane Bourque, a doctoral student at Université de Montréal's Department of Psychiatry. "Although they may be infrequent and thus not problematic for the adolescent, when these experiences are reported continuously, year after year, then there's an increased risk of a first psychotic episode or another psychiatric condition."
She added: "Our findings confirm that becoming a more regular marijuana user during adolescence is, indeed, associated with a risk of psychotic symptoms. This is a major public-health concern for Canada."
What are the underlying mechanisms?
One of the study's objectives was to better understand the mechanisms by which marijuana use is associated with psychotic-like experiences. Bourque and her supervisor, Dr. Patricia Conrod at Sainte Justine University Hospital Research Centre hypothesized that impairments in cognitive development due to marijuana misuse might in turn exacerbate psychotic-like experiences.
This hypothesis was only partially confirmed, however. Among the different cognitive abilities evaluated, the development of inhibitory control was the only cognitive function negatively affected by an increase in marijuana use. Inhibitory control is the capacity to withhold or inhibit automatic behaviours in favor of a more contextually appropriate behaviour. Dr. Conrod's team has shown that this specific cognitive function is associated with risk for other forms of substance abuse and addiction.
"Our results show that while marijuana use is associated with a number of cognitive and mental health symptoms, only an increase in symptoms of depression -- such as negative thoughts and low mood -- could explain the relationship between marijuana use and increasing psychotic-like experiences in youth," Bourque said.
What's next
These findings have important clinical implications for prevention programs in youth who report having persistent psychotic-like experiences. "While preventing adolescent marijuana use should be the aim of all drug strategies, targeted prevention approaches are particularly needed to delay and prevent marijuana use in young people at risk of psychosis," said Patricia Conrod, the study's senior author and a professor at UdeM's Department of Psychiatry.
Conrod is optimistic about one thing, however: the school-based prevention program that she developed, Preventure, has proven effective in reducing adolescent marijuana use by an overall 33%. "In future programs, it will be important to investigate whether this program and other similar targeted prevention programs can delay or prevent marijuana use in youth who suffer from psychotic-like experiences," she said. "While the approach seems promising, we have yet to demonstrate that drug prevention can prevent some cases of psychosis."
A large youth cohort from Montreal
The study's results are based on the CIHR-funded Co-Venture project, a cohort of approximately 4,000 adolescents aged 13 years old from 31 high schools in the Greater Montreal area. These teens are followed annually from Grade 7 to Grade 11. Every year they fill out computerized questionnaires to assess substance use and psychiatric symptoms. The teens also complete cognitive tasks to allow the researchers to evaluate their IQ, working memory and long-term memory as well as their inhibitory control skills.
To do their study, the research team first confirmed results from both the United Kingdom and Netherlands showing the presence of a small group of individuals (in Montreal, 8%) among the general population of adolescents who report recurrent psychotic-like experiences. Second, the researchers explored how marijuana use between 13 and 16 years of age increases the likelihood of belonging to the 8%. Finally, they examined whether the relationship between increasing use of marijuana and increasing psychotic-like experiences can be explained by emerging symptoms of anxiety or depression, or by the effects of substance use on developing cognitive abilities.
https://www.sciencedaily.com/releases/2017/07/170705104042.htm
Why pot-smoking declines, but doesn't end, with parenthood
June 1, 2017
Science Daily/University of Washington
Adults who smoke marijuana often cut back after becoming parents -- but they don't necessarily quit.
The influence of a significant other and positive attitudes toward the drug overall, in addition to the onset of parenthood, also are factors in whether someone uses marijuana.
It's a changing landscape for marijuana use, as laws ease and cultural acceptance grows -- in Washington state and elsewhere around the country. Against that backdrop, the study by the University of Washington's Social Development Research Group (SDRG) aims to present information about marijuana use among parents and nonparents alike.
"When it comes to adults, we don't know long-term consequences of moderate marijuana use in the legal context, so that we cannot say that we absolutely must intervene," explained Marina Epstein, a UW research scientist and lead author of the study. "However, when it comes to parents, their use is strongly related to their children's marijuana use, and that is a significant problem, since adolescent marijuana use can be harmful. Our study wanted to prepare us to build effective interventions for all adults if it becomes an issue."
The study, published online May 19 in Prevention Science, surveyed 808 adults (parents and nonparents), a group the SDRG first identified as fifth-graders at Seattle elementary schools in the 1980s as part of a long-term research project. For the marijuana study, participants were interviewed at specific intervals over a 12-year period, ending when most participants were 39 years old. That survey concluded in 2014 -- two years after marijuana was legalized in Washington. A parent-only subset of 383 people was surveyed at separate times, ending in 2011, just before the statewide vote that gave rise to pot shops.
Women and people of color made up approximately half the big study pool; of the parent subsample, about 60 percent were women, and an equivalent percentage were people of color.
The increasing availability of marijuana, along with shifting societal opinions about it, lends a timeliness to the findings and provides potential for further study, Epstein said. What factors affect behavior, especially among parents? Past studies have linked parenthood with decreased marijuana use; what makes this one different is the examination of other influences, too, and how those might inform intervention strategies.
More than half of Americans now support legalizing marijuana, according to a 2015 Pew Research Center report, and data from 2014 indicate a majority of Americans view alcohol as more damaging to a person's health than pot.
Meanwhile, concerns about the health effects of marijuana tend to focus on children and teens -- years when the brain is still developing. The Centers for Disease Control and Prevention and the National Institute on Drug Abuse stress the potential for long-term cognitive impairment, problems with attention and coordination and other risk-taking behaviors due to heavy marijuana use. For those reasons, medical professionals recommend that parents avoid using marijuana -- or drinking heavily -- around kids to prevent modeling the behavior.
The UW research found that, in general, a greater percentage of nonparents reported using marijuana in the past year than parents. At age 27, for example, 40 percent of nonparents said they had smoked pot, compared to about 25 percent of parents. By participants' early 30s, their marijuana use had declined, but a gap between the two groups remained: Slightly more than 16 percent of parents said they smoked pot in the past year, while 31 percent of nonparents reported the same.
But the study also showed that participants who started using marijuana as young adults were much more likely to continue to use into their mid- to late 30s, even after they became parents. Having a partner who used marijuana also increased the likelihood of participants' continued use. Those trends were true of both parents and nonparents, demonstrating the impact of attitudes and the behavior of others, Epstein said.
"This shows that we need to treat substance use as a family unit. It isn't enough that one person quits; intervention means working with both partners," she said. "We also need to tackle people's positive attitudes toward marijuana if we want to reduce use."
And while the health risks to adults are being debated, the focus on children can be a driver for prevention campaigns, Epstein said.
https://www.sciencedaily.com/releases/2017/06/170601124057.htm