New research shows a clear link between early and regular cannabis use by youth and alterations in brain circuits that support aspects of executive functioning.
The study finds that the frequent and regular use of cannabis in youth alters the neural circuits by which the mind governs, regulates, and guides behaviors, impulses and decision-making based on goals.
The researchers found that these brain alterations were less intense in individuals who recently stopped using cannabis.
However, the alterations were greater and more persistent in individuals who started using cannabis earlier, while the brain is still developing.
The study was published in the Journal of the American Academy of Child and Adolescent Psychiatry.
“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, Ph.D., a postdoctoral scientist with Columbia University.
“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.”
The study’s findings are based on functional magnetic resonance imaging (fMRI) data acquired from 28 adolescents and young adults between the ages of 14 and 23 with significant cannabis use and 32 age and sex-matched people who don’t use cannabis.
Participants were scanned during their performance of a Simon Spatial Incompatibility Task, a cognitive control task that requires resolving cognitive conflict to respond accurately, the researchers reported.
Compared to the non-users, the adolescents and young adults with significant cannabis use showed reduced activation in the frontostriatal circuits that support cognitive control and conflict resolution, according to the study’s findings.
The researchers also examined to what extent the regions in the frontostriatal circuit were functionally connected. Although circuit connectivity did not differ between cannabis-using and non-using youth, the researchers found an association between how early individuals began regularly using cannabis and the extent to which frontostriatal regions were disrupted.
This suggests that earlier chronic use may have a larger impact on circuit development than use at a later age, they said.
“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 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.
Cyr noted that substance use and relapse rates are associated with control processes. Because of this, she said, “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.”
Cyr is a scientist in the Division of Child and Adolescent Psychiatry at the New York State Psychiatric Institute and the Vagelos College of Physicians & Surgeons at Columbia.
Photo: Conflict-related neural activations. Between-group t-map of conflict-related activations (voxel-wise cluster-defining threshold of p < .001, familywise error-corrected cluster extent correction of p < .05) and within-group t-maps (cluster-defining threshold of p < .001, uncorrected), adjusting for age and gender. ACC = anterior cingulate cortex; CU = cannabis user; HC = healthy control; MCC = middle cingulate cortex; OFC = orbitofrontal cortex; PCG = postcentral gyrus; PreCu = precuneus; SMG = supramarginal gyrus; Thal = thalamus. Credit: Elsevier.