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

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