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

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

CBD may protect against psychiatric risk from high-THC cannabis strains

Neuroscientists find cannabidiol reduces symptoms such as impaired memory in adolescent mice simultaneously exposed to THC

September 6, 2017

Science Daily/Indiana University

A study reported Sept. 5 by neuroscientists at Indiana University finds that a non-psychoactive compound in cannabis called cannabidiol, or CBD, appears to protect against the long-term negative psychiatric effects of THC, the primary psychoactive ingredient in cannabis.

Other research has shown that long-term use of cannabis increases adolescent drug users' risk for certain psychiatric and neurological disorders, such as schizophrenia. The risk to teens is greater than ever since selective breeding of plants to produce higher levels of THC over the past several decades has substantially increased exposure to the compound.

"This study confirms in an animal model that high-THC cannabis use by adolescents may have long-lasting behavioral effects," said lead author Dr. Ken Mackie, professor in the IU College of Arts and Sciences' Department of Psychological and Brain Sciences and director of the Linda and Jack Gill Center for Biomolecular Science at IU Bloomington. "It also suggests that strains of cannabis with similar levels of CBD and THC would pose significantly less long-term risk due to CBD's protective effect against THC."

THC, or tetrahydrocannabinol, is the chemical in cannabis that causes the "high" experienced during its use. Cannabis with higher levels of THC possess lower levels of the protective CBD, and vice versa, due to a biological link between THC and CBD production in the plant. An analysis of cannabis seized by the U.S. Drug Enforcement Administration found that while THC levels rose 300 percent from 1995 to 2014, the levels of CBD have declined 60 percent.

In contrast to THC, CBD does not cause a "high." It is also an important ingredient in medical cannabis. For example, CBD appears useful as a treatment for some forms of severe childhood epilepsy, and its use for severe epilepsy was approved by the Indiana legislature this year.

"This is the first study in a rigorously controlled animal model to find that CBD appears to protect the brain against the negative effects of chronic THC," Mackie said. "This is especially important since heavy use of cannabis with higher levels of THC poses a serious risk to adolescents."

To conduct their study, IU researchers divided adolescent or adult male mice into five groups. Three groups received 3 milligrams per kilogram of body weight of either THC, CBD, or THC with CBD every day for three weeks. The other two groups received a placebo or no treatment.

All mice were then tested for signs of impaired memory, obsessive-compulsive behaviors and anxiety immediately following treatment as well as six weeks after treatment.

The mice exposed to THC alone showed signs of impaired memory and increased obsessive-compulsive behavior immediately after treatment. The adolescent group still experienced these changes six weeks after treatment, whereas the adult group did not. Both groups experienced a long-term increase in anxiety.

By contrast, adult and adolescent mice exposed to CBD alone showed no behavioral changes immediately or six weeks after treatment. Most significantly, mice in both age groups that received CBD with THC exhibited no short- or long-term behavioral changes. These results suggest that long-term use of cannabis strains containing similar amounts of CBD and THC may be less harmful than long-term use of high-THC strains.

https://www.sciencedaily.com/releases/2017/09/170906135554.htm