Adolescent cannabis use may alter neurodevelopment

Cannabis use in middle to late adolescence may alter neurodevelopment, according to study results published in JAMA Psychiatry.

“Extant research studies suggest that changes in endocannabinoid signaling can have a significant association with aspects of mammalian brain development,” Matthew D. Albaugh, PhD, of the department of psychiatry at the University of Vermont Larner College of Medicine, and colleagues wrote. “Evidence further indicates that the adolescent brain may be particularly sensitive to disruptions in normative fluctuations in endocannabinoid signaling, associated with altered neurodevelopment and behavior. Despite such findings in the animal literature, few longitudinal neuroimaging studies have examined putative ties between cannabis use and adolescent brain development, to our knowledge.”

The researchers aimed to evaluate the potential associations between MRI-assessed cerebral cortical thickness development and cannabis use among a longitudinal sample of 799 adolescents (56.3% female; mean age, 14.4 years at baseline and 19 years at follow-up) who reported being cannabis naive at study baseline and who had behavioral and neuroimaging data available at baseline and 5-year follow-up. They collected data via the community-based IMAGEN cohort study that was conducted across eight European sites. Baseline data included in the current study were collected between March 2008 and December 2011, and follow-up data between January 2013 and December 2016. Participants reported cannabis use at baseline and 5-year follow-up using the European School Survey Project on Alcohol and Other Drugs, and their anatomical MR images were acquired via a three-dimensional T1-weighted magnetization prepared gradient echo sequence.

Results showed a negative association between cannabis use and thickness in left prefrontal and right prefrontal cortices at 5-year follow-up. The researchers noted lifetime cannabis use at 5-year follow-up did not have significant associations with baseline cortical thickness, which suggested that the observed neuroanatomical differences did not precede cannabis use initiation. According to longitudinal analysis, age-related cortical thinning was qualified by cannabis use in a dose-dependent fashion, with greater use from baseline to follow-up linked to increased thinning in left prefrontal and right prefrontal cortices. Albaugh and colleagues observed an association between the spatial pattern of cannabis-related thinning and age-related thinning in this sample, as well as a positron emission tomography-assess cannabinoid 1 receptor-binding map derived via a separate sample of participants. From baseline to follow-up, thinning in right prefrontal cortices appeared linked to attentional impulsiveness at follow-up.

“The findings underscore the importance of further longitudinal studies of adolescent cannabis use, particularly given increasing trends in the legalization of recreational cannabis use,” Albaugh and colleagues wrote.