Polysubstance Use Plays a Key Role in Midlife Structural Brain Alterations in Long-term Cannabis Users

Abstract

Approximately 147 million people across the world consume cannabis annually, making it the most commonly used illicit drug globally ( 1 World Health Organization Alcohol, Drugs, and Addictive Behaviours Unit. Cannabis.. https://www.who.int/teams/mental-health-and-substance-use/alcohol-drugs-and-addictive-behaviours/drugs-psychoactive/cannabisDate accessed: August 8, 2022 Google Scholar ). Although the use of cannabis has generally become more accepted and perceptions of harm have been decreasing in recent years ( 2 Patrick M.E. Schulenberg J.E. Miech R.A. Johnston L.D. O’Malley P.M. Bachman J.G. Monitoring the Future Panel Study annual report: National data on substance use among adults ages 19 to 60, 1976-2021. Monitoring the Future Monograph Series. University of Michigan Institue for Social Research, Ann Arbor, MI2022 Google Scholar ), negative effects of cannabis use on health and well-being have been identified. Cannabis use has been found to be associated with neurocognitive deficits in memory, learning, and attention and to contribute to alterations to both brain function and structure [see Volkow et al. ( 3 Volkow N.D. Swanson J.M. Evins A.E. DeLisi L.E. Meier M.H. Gonzalez R. et al. Effects of cannabis use on human behavior, including cognition, motivation, and psychosis: A review. JAMA Psychiatry. 2016; 73: 292-297 Crossref PubMed Scopus (480) Google Scholar ) for review]. However, existing studies examining the neural correlates of cannabis use have produced mixed findings in relation to cannabis-specific effects. The question of whether—and to what extent—cannabis use produces unique neural detriments compared with other psychoactive substances remains largely unknown. A possible reason for this knowledge gap is that there are likely other variables at play, variables that are often unaccounted for, that confound direct associations between cannabis use and neural outcomes. Pulling from literature at the intersection of developmental science, addiction research, and neuroscience, two likely targets are age and polysubstance use. SEE CORRESPONDING ARTICLE ON PAGE 861 Diminished Structural Brain Integrity in Long-term Cannabis Users Reflects a History of Polysubstance UseBiological PsychiatryVol. 92Issue 11PreviewCannabis legalization and use are outpacing our understanding of its long-term effects on brain and behavior, which is fundamental for effective policy and health practices. Existing studies are limited by small samples, cross-sectional measures, failure to separate long-term from recreational use, and inadequate control for other substance use. Here, we address these limitations by determining the structural brain integrity of long-term cannabis users in the Dunedin Study, a longitudinal investigation of a population-representative birth cohort followed to midlife. Full-Text PDF