Teen Cannabis Use Not Without Risk to Cognitive Development

Summary: A new study reports the lasting effects of teen cannabis use can be observed on important cognitive function and appears to have a more pronounced effect than alcohol use on neurodevelopment.

Source: University of Montreal.

Although studies have shown that alcohol and cannabis misuse are related to impaired cognition in youth, previous studies were not designed to understand this relationship and differentiate whether cannabis use was causal or consequential to cognitive impairment. A new study by researchers at CHU Sainte-Justine and Université de Montréal, published in the American Journal of Psychiatry, shows that beyond the role of cognition in vulnerability to substance use, the concurrent and lasting effects of adolescent cannabis use can be observed on important cognitive functions and appear to be more pronounced than those observed for alcohol.

Beyond acute intoxicating effects, alcohol and cannabis misuse has been associated with impairments in learning, memory, attention and decision-making, as well as with lower academic performance. “While many studies have reported group differences in cognitive performance between young users and non-users, what had yet to be established was the causal and lasting effects of teen substance use on cognitive development,” said co-author and PhD student at Université de Montréal, Jean-François G. Morin. Senior author and investigator Dr. Patricia Conrod, from the Department of Psychiatry at Université de Montréal, added that “very few studies are designed to look at this question from a developmental perspective. Our study is unique in that it followed a large sample of high school students from 7th to 10th grade using cognitive and substance-use measures. Using this big-data approach, we were able to model the complex nature of the relationship between these sets of variables.”

To understand the relationship between alcohol, cannabis use and cognitive development among adolescents at all levels of consumption (abstinent, occasional consumer or high consumer), the research team followed a sample of 3,826 Canadian adolescents over a period of four years. Using a developmentally sensitive design, the authors investigated relationships between year-to-year changes in substance use and cognitive development across a number of cognitive domains, such as recall memory, perceptual reasoning, inhibition and working memory. Multi-level regression models were used to simultaneously test vulnerability and concurrent and lasting effects on each cognitive domain. The study found that vulnerability to cannabis and alcohol use in adolescence was associated with generally lower performance on all cognitive domains.

“However, further increases in cannabis use, but not alcohol consumption, showed additional concurrent and lagged effects on cognitive functions, such as perceptual reasoning, memory recall, working memory and inhibitory control,” Conrod said. “Of particular concern was the finding that cannabis use was associated with lasting effects on a measure of inhibitory control, which is a risk factor for other addictive behaviours, and might explain why early onset cannabis use is a risk factor for other addictions.” Morin added: “Some of these effects are even more pronounced when consumption begins earlier in adolescence.”

a marijuana plant
Beyond acute intoxicating effects, alcohol and cannabis misuse has been associated with impairments in learning, memory, attention and decision-making, as well as with lower academic performance. NeuroscienceNews.com image is in the public domain.

In a context where policies and attitudes regarding substance use are being reconsidered, this research highlights the importance of protecting youth from the adverse effects of consumption through greater investment in drug-prevention programs.

“It will be important to conduct similar analyses with this cohort or similar cohorts as they transition to young adulthood, when alcohol and cannabis use become more severe,” Conrod said. “This might be particularly relevant for alcohol effects: while this study did not detect effects of teen alcohol consumption on cognitive development, the neurotoxic effects may be observable in specific subgroups differentiated based on the level of consumption, gender or age.” Morin added: “We also want to identify if these effects on brain development are related to other difficulties such as poor academic performance, neuroanatomical damage, and the risk of future addiction or mental health disorders.”

[divider]About this neuroscience research article[/divider]

The first author is Jean-François G. Morin, B.A., a doctoral student under Patricia Conrod’s supervision. Senior author is Patricia Conrod, Ph.D., Researcher and Director of the Venture laboratory at CHU Sainte-Justine, Full Professor in the Department of Psychiatry of Université de Montréal and holder of the Chair Dr Julien/Fondation Marcelle and Jean Coutu in Social and Community Pediatrics of Université de Montréal.

Funding: This study was funded by the Canadian Institutes of Health Research, the Fonds de recherche du Québec – Santé, the Social Sciences and Humanities Research Council of Canada and the Canada Research Chair program. The authors report no financial relationships with commercial interests.

Source: Patsy Coulanges – University of Montreal
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Abstract for “A Population-Based Analysis of the Relationship Between Substance Use and Adolescent Cognitive Development” by Jean-François G. Morin, B.A., Mohammad H. Afzali, Ph.D., Josiane Bourque, M.Sc., Sherry H. Stewart, Ph.D., Jean R. Séguin, Ph.D., Maeve O’Leary-Barrett, Ph.D., and Patricia J. Conrod, Ph.D. in American Journal of Psychiatry. Published October 3 2018.
doi:10.1176/appi.ajp.2018.18020202

[divider]Cite This NeuroscienceNews.com Article[/divider]

[cbtabs][cbtab title=”MLA”]University of Montreal”Teen Cannabis Use Not Without Risk to Cognitive Development.” NeuroscienceNews. NeuroscienceNews, 3 October 2018.
<https://neurosciencenews.com/teen-cognition-cannabis-9952/>.[/cbtab][cbtab title=”APA”]University of Montreal(2018, October 3). Teen Cannabis Use Not Without Risk to Cognitive Development. NeuroscienceNews. Retrieved October 3, 2018 from https://neurosciencenews.com/teen-cognition-cannabis-9952/[/cbtab][cbtab title=”Chicago”]University of Montreal”Teen Cannabis Use Not Without Risk to Cognitive Development.” https://neurosciencenews.com/teen-cognition-cannabis-9952/ (accessed October 3, 2018).[/cbtab][/cbtabs]


Abstract

A Population-Based Analysis of the Relationship Between Substance Use and Adolescent Cognitive Development

Alcohol and cannabis misuse are related to impaired cognition. When inferring causality, four nonexclusive theoretical models can account for this association: 1) a common underlying vulnerability model; 2) a neuroplasticity model in which impairment is concurrent with changes in substance use but temporary because of neuroplastic brain processes that restore function; 3) a neurotoxicity model of long-term impairment consequential to substance use; and 4) a developmental sensitivity hypothesis of age-specific effects. Using a developmentally sensitive design, the authors investigated relationships between year-to-year changes in substance use and cognitive development.

Method:
A population-based sample of 3,826 seventh-grade students from 31 schools consisting of 5% of all students entering high school in 2012 and 2013 in the Greater Montreal region were assessed annually for 4 years on alcohol and cannabis use, recall memory, perceptual reasoning, inhibition, and working memory, using school-based computerized assessments. Multilevel regression models, performed separately for each substance, were used to simultaneously test vulnerability (between-subject) and concurrent and lagged within-subject effects on each cognitive domain.

Results:
Common vulnerability effects were detected for cannabis and alcohol on all domains. Cannabis use, but not alcohol consumption, showed lagged (neurotoxic) effects on inhibitory control and working memory and concurrent effects on delayed memory recall and perceptual reasoning (with some evidence of developmental sensitivity). Cannabis effects were independent of any alcohol effects.

Conclusions:
Beyond the role of cognition in vulnerability to substance use, the concurrent and lasting effects of adolescent cannabis use can be observed on important cognitive functions and appear to be more pronounced than those observed for alcohol.

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  1. I in no way endorse the carte blanche use of Cannabis; but the range of effects that Phytocannabinoids have on the human endocannabinoid system are not only vast, they are virtually all beneficial to human health.

    As we continue to sort through the emerging science of cannabis and cannabinoids, one thing remains clear: a functional cannabinoid system is essential for health. From embryonic implantation on the wall of our mother’s uterus, to nursing and growth, to responding to injuries, endocannabinoids help us survive in a quickly changing and increasingly hostile environment.

    There is absolutely no evidence that Cannabis use during adolescence causes ‘irreparable’ brain damage but there is universal evidence of the long term damage of alcohol use, as well as tobacco.

    The ironic thing about the claim that cannabis use is destroying the Adolescent brain is that all of the studies that point to alterations in brain structure in the hippocampus, or other areas of the brain, fail to acknowledge that even though the regions of the brain do appear to slightly alter in structure in some users of cannabis, they also increase the number of neurons and neurotransmission improves.

    It is pervasive institutionalized negative bias against all forms of cannabis use that results in selective information regarding the claim that alteration of brain structure is deleterious and permanent; And, They fail to mention the positive indications of increased neural activity and efficiency.

    FYI
    Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies

    vol. 113 no. 5
    > Nicholas J. Jackson, E500–E508
    there was no evidence of a dose–response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings. Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment.

    https://www.ncbi.nlm.nih.gov/pubmed/26787878

    FYI
    Daily Marijuana Use Is Not Associated with Brain Morphometric Measures in Adolescents or Adults
    Barbara J. Weiland, Rachel E. Thayer, Brendan E. Depue, Amithrupa Sabbineni, Angela D. Bryan and Kent E. Hutchison
    Journal of Neuroscience 28 January 2015, 35 (4) 1505-1512;

    In sum, the results indicate that, when carefully controlling for alcohol use, gender, age, and other variables, there is no association between marijuana use and standard volumetric or shape measurements of subcortical structures.

    http://www.jneurosci.org/content/35/4/1505

    FYI
    The American Psychological Association
    August 4, 2015
    Teen Marijuana Use Not Linked to Later Depression, Lung Cancer, Other Health Problems, Research Finds

    “What we found was a little surprising,” said lead researcher Jordan Bechtold, PhD, a psychology research fellow at the University of Pittsburgh Medical Center. “There were no differences in any of the mental or physical health outcomes that we measured regardless of the amount or frequency of marijuana used during adolescence.”

    http://www.apa.org/news/press/releases/2015/08/marijuana-use.aspx

    FYI
    Adolescent cannabis use and brain systems supporting adult working memory encoding, maintenance, and retrieval

    BrendenTervo-Clemmensa Daniel Simmonds Finnegan J. Calabrode Nancy L.Dayd Gale A.Richardsond Beatriz Luna

    Department of Psychology, University of Pittsburgh, United States
    Center for the Neural Basis of Cognition, Pittsburgh, United States
    Center for Neuroscience, University of Pittsburgh, United States
    Department of Psychiatry, University of Pittsburgh, United States
    Department of Bioengineering, University of Pittsburgh, United States

    However, cannabis age of onset brain-behavior associations did not differ between groups with a single reported use and those with repeated use, suggesting age of onset effects may reflect substance use risk characteristics rather than a developmentally-timed cannabis exposure effect. Within repeated cannabis users, greater levels of total cannabis use were associated with performance-related increases in dorsolateral prefrontal cortex (DLPFC) activation during maintenance. This pattern of significant results remained unchanged with inclusion of demographic and prenatal measures as covariates. Surprisingly, however, at the group level, cannabis users generally performed better than participants who reported never using cannabis (faster RT, higher accuracy).

    https://www.ncbi.nlm.nih.gov/pubmed/29253654

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