Early-and-regular cannabis use by youth is associated with alteration in brain circuits that support cognitive control
June 20, 2019
Science Daily/Elsevier
The development of neural circuits in youth, at a particularly important time in their lives, can be heavily influenced by external factors -- specifically the frequent and regular use of cannabis. A new study in the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP), published by Elsevier, reports that alterations in cognitive control -- an ensemble of processes by which the mind governs, regulates and guides behaviors, impulses, and decision-making based on goals are directly affected.
The researchers found that these brain alterations were less intense in individuals who recently stopped using cannabis, which may suggest that the effects of cannabis are more robust in recent users. Additional findings from the study also suggest greater and more persistent alterations in individuals who initiated cannabis use earlier, while the brain is still developing.
"Most adults with problematic substance use now were most likely having problems with drugs and alcohol in adolescence, a developmental period during which the neural circuits underlying cognitive control processes continue to mature," said lead author Marilyn Cyr, PhD. "As such, the adolescent brain may be particularly vulnerable to the effects of substance use, particularly cannabis -- the most commonly used recreational drug by teenagers worldwide," added the postdoctoral scientist in the Division of Child and Adolescent Psychiatry at the New York State Psychiatric Institute, Vagelos College of Physicians & Surgeons, Columbia University, New York.
The findings are based on functional magnetic resonance imaging (fMRI) data acquired from 28 adolescents and young adults (aged 14-23 years) with significant cannabis use and 32 age and sex-matched non-using healthy controls. Participants were scanned during their performance of a Simon Spatial Incompatibility Task, a cognitive control task that requires resolving cognitive conflict to respond accurately.
Compared to their healthy counterparts, the adolescents and young adults with significant cannabis use showed reduced activation in the frontostriatal circuits that support cognitive control and conflict resolution.
The authors also examined the degree to which fluctuations in activity in relation to conflict resolution is synchronized across the different regions comprised in this frontostriatal circuit (that is, to what extent are regions functionally connected with each other). Although circuit connectivity did not differ between cannabis-using and non-using youth, the research team found an association between how early individuals began regularly using cannabis and the extent to which frontostriatal regions were disrupted, suggesting that earlier chronic use may have a larger impact on circuit development than use of later onset.
"The present findings support the mission of the Adolescent Brain and Cognitive Development study, a longitudinal study aimed at understanding the developmental trajectory of brain circuits in relation to cannabis use," said Dr. Cyr. "In addition, these findings are a first step towards identifying brain-based targets for early interventions that reduce addiction behaviors by enhancing self-regulatory capacity.
"Given that substance use and relapse rates are associated with control processes, interventions based on neural stimulation, such as transcranial magnetic stimulation (TMS), and behavioral interventions, such as cognitive training, that specifically target the brain circuits underlying these control processes may be helpful as adjunct intervention strategies to complement standard treatment programs for cannabis use disorder."
https://www.sciencedaily.com/releases/2019/06/190620104858.htm
Depression among young teens linked to cannabis use at 18
Seattle-focused study suggests earlier intervention with depressed youths could reduce rate of cannabis-use disorder
July 17, 2017
Science Daily/University of Washington Health Sciences/UW Medicine
A study looking at the cumulative effects of depression in youth, found that young people with chronic or severe forms of depression were at elevated risk for developing a problem with cannabis in later adolescence.
The study led by UW Medicine researchers interviewed 521 students recruited from four Seattle public middle schools. Researchers used data from annual assessments when students were ages 12-15 and then again when they were 18. The results were published in the journal Addiction.
"The findings suggest that if we can prevent or reduce chronic depression during early adolescence, we may reduce the prevalence of cannabis use disorder," said lead author Isaac Rhew, research assistant professor of psychiatry and behavioral sciences at the University of Washington School of Medicine.
What researchers called "a 1 standard deviation increase" in cumulative depression during early adolescence was associated with a 50 percent higher likelihood of cannabis-use disorder.
According to researchers, during the past decade cannabis has surpassed tobacco with respect to prevalence of use among adolescents. Cannabis and alcohol are the two most commonly used substances among youth in the United States. They pointed to one national study showing increases in prevalence of cannabis use disorder and alcohol use disorder in the United States, especially among young adults.
Longitudinal studies looking at the link between depression and later use of alcohol and cannabis, however, have been mixed. Some show a link. Others don't. But most studies have assessed adolescent depression at a single point in time -- not cumulatively, said the researchers. Further, there have been differences in how substance use has been measured ranging from the initiation of any use to heavier problematic forms of use.
The study oversampled for students with depressive and/or conduct problems. The researchers were surprised to see that the prevalence of cannabis and alcohol use disorder in this study was notably higher than national estimates with 21 percent meeting criteria for cannabis use disorder and 20 percent meeting criteria for alcohol use disorder at age 18.
What effect the easing of marijuana laws in Washington state had on the youth is unclear. Researchers said it would be informative to conduct a similar study in a state with more strict marijuana laws to understand whether the relationship between depression and cannabis misuse would still hold in areas where marijuana may be less accessible.
The age 18 substance abuse assessments occurred between 2007-2010. Washington state legalized medical cannabis in 1998 and its medical cannabis market expanded greatly after 2009 when the federal justice department issued a ruling known as the Ogden Memo. And in 2003, the city of Seattle made cannabis offenses the lowest enforcement priority for police and the city attorney.
https://www.sciencedaily.com/releases/2017/07/170717151031.htm
Cannabis use disorder: The policy climate matters
January 23, 2019
Science Daily/Columbia University's Mailman School of Public Health
Adolescents and young adults living in states with more liberal policies reported higher average rates of past-year cannabis use than those in states with more conservative policies. However, the rates of cannabis use disorder -- abuse or dependence on the drug -- were significantly lower in states with more liberal policies compared to states with more conservative policies. The study is one of the first to assess the relationship between policy liberalism and health outcomes, and specifically cannabis use-related outcomes.
Adolescents and young adults living in states with more liberal policies reported higher average rates of past-year cannabis use than those in states with more conservative policies, according to a new study conducted at Columbia University Mailman School of Public Health. However, the rates of cannabis use disorder -- abuse or dependence on the drug -- were significantly lower in states with more liberal policies compared to states with more conservative policies, for ages 12 to 17, and marginally lower for ages 26 and older. These results remained significant even when controlling for the presence of medical cannabis laws. This study is one of the first to assess the relationship between policy liberalism and health outcomes, and specifically cannabis use-related outcomes. The findings are published in the International Journal of Drug Policy.
"The majority of existing work has explored the relationship between medical cannabis laws and cannabis outcomes, whereas our results identified important relationships between the state-level policy context as a whole, and cannabis use outcomes," said Morgan Philbin, PhD, assistant professor of Sociomedical Sciences, and first author. "While this research does not suggest that being in a liberal state causes people to use cannabis, or have lower rates of cannabis use disorder, it does highlight how states may differ beyond substance use policies, and how these differences also merit attention."
Using nationally-representative state-level data, the researchers examined the associations between policy liberalism and cannabis use and cannabis use disorder among past year users. Data were obtained for ages 12-17, 18-25, and 26 and older from the 2004-2006 and 2010-2012 National Survey on Drug Use and Health.
Past year cannabis use was consistently higher in liberal compared to conservative states, and remained significantly higher for ages 12-17 and 18-25 after adjusting for medical cannabis law status. As of December 2018, a total of 33 states had approved medical cannabis laws and eight states plus Washington, D.C. had legalized cannabis use.
Prevalence of cannabis use has increased overall since 2007 which has raised concerns about potential negative consequences associated with problematic use, specifically cannabis use disorder. "These latest findings could directly inform policymakers and public health practitioners about the degree to which other broader contextual factors also influence cannabis use patterns in the U.S.," noted Philbin.
States were categorized as liberal, moderate, or conservative based on the 2005 and 2011 State Rank on Policy Liberalism Index, which is based on policy indicators for which liberals and conservatives commonly differ. The Index ranked each state from 1 (most liberal) to 50 (most conservative) based on its policies regulating gun control, abortion access, Temporary Assistance to Needy families, collective bargaining, and tax structure.
Average state-level prevalence of past-year cannabis use by age was lowest for ages 26 and older and highest for ages 18 to 25 throughout the study period. Average prevalence increased for ages 18-25 in liberal states, from 33 percent to 37 percent, and rose marginally in conservative states, from 25 percent to 26 percent. The same pattern of use was observed for ages 26 and over in liberal (8 percent to 10 percent) and conservative (6 percent to 7 percent) states. For ages 12-17, however, past year use did not significantly change from 2004-2006 to 2010-2012 in liberal or conservative states.
In contrast, cannabis use disorder among past-year cannabis users decreased from 2004-2006 to 2010-2012 among those aged 18-25 in conservative states (22 percent to 18 percent) and liberal states (20 percent to 17 percent). Among individuals ages 26 and over, cannabis use disorder among past-year users decreased in liberal states (11 percent to 8 percent). For 12-17 year olds, cannabis use disorder decreased in conservative states (28 percent to 25 percent), though still remained marginally higher than in liberal states (24 percent).
"Our study highlights the need for researchers and public health professionals to distinguish between cannabis use and cannabis use disorder when interacting with patients at the individual level and when developing primary prevention strategies and interventions at the population level," said Silvia Martins, MD, PhD, associate professor of Epidemiology and senior author. "This line of research not only helps identify how state-level policies as a whole impact cannabis use outcomes, but ultimately supports the development of more health-promoting policies."
The work was funded by the National Institutes of Health/National Institute on Drug Abuse (DA037866, DA039804A, DA031099).
Co-authors are Pia Mauro, Julian Santaella-Tenorio, Christine Mauro, and Elizabeth Kinnard, Columbia Mailman School; and Magdalena Cerdá, New York University.
https://www.sciencedaily.com/releases/2019/01/190123091158.htm