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

Early use of marijuana can increase its negative health impacts

A study cautions of risks for young consumers

March 28, 2017

Science Daily/Concordia University

With new legislation imminent in Canada, marijuana is a hot topic these days. Those who smoke it may be cheering. Those who've never tried it may be thinking, why not? And those looking to make a business out of it are grappling with how to navigate a challenging product.

But one of the most contentious aspects of legalization is age. A report by the Canadian Task Force on Cannabis Legalization and Regulation, released in December 2016, recommends marijuana use be restricted to those 18 years old and older.

The need for age guidelines falls in line with a new study by James McIntosh, professor of economics in the Faculty of Arts and Science. Recently published in the journal Health, the findings show that young users report the most impact to their physical and mental health.

The article also shows that those who wait until the age of 21 to use the drug are unlikely to develop a lifelong habit.

Heightened risks for youth

For the study, McIntosh and his co-author Rawan Hassunah (BA 16) examined the results of three national surveys on tobacco, alcohol and drug use -- two in Canada and one in the United States.

"We wanted to see what the effects of regular marijuana use were on self-reported physical and mental health," McIntosh explains.

The report cites other studies demonstrating the negative impacts of marijuana. It's the first, however, to look so closely at age of first use.

In terms of overall effects, the study confirmed that marijuana does affect people's physical and mental health, that it will cause cognitive impairment, memory loss, diminished IQ, limited educational success and likelihood for developing mental illness. Physically, early users also suffer higher rates of respiratory diseases and certain cancers.

McIntosh says the younger you start, the worse the impacts.

"We found that if age of first use is below 15, it's always bad for you."

The argument for legalization

So how can these findings translate into informing youth about the risks? Besides legislation, McIntosh recommends educational programs, counselling services and a distribution system that minimizes use by young people.

Despite his warnings about age restrictions, however, he says legalization will bring more good than harm.

"The task force outlines these benefits -- to take marijuana out of criminal hands, to tax it, to make sure that product quality is preserved."

McIntosh adds that being at the cusp of legalization puts Canada in a unique position to begin rigorous study of cannabis and its effects.

"We need to start collecting data on it to see what the effects are on people of all ages. You can get all kinds of information on drinking behaviours -- they should do that with marijuana."

https://www.sciencedaily.com/releases/2017/03/170328105901.htm