January 16, 2018
New study in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging looks at the effects of heavy cannabis use on brain function and behavior
Young people with cannabis dependence have altered brain function that may be the source of emotional disturbances and increased psychosis risk that are associated with cannabis abuse, according to a new study published in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging. The alterations were most pronounced in people who started using cannabis at a young age. The findings reveal potential negative long-term effects of heavy cannabis use on brain function and behavior, which remain largely unknown despite the drug's wide use and efforts to legalize the substance.
"These brain imaging data provide a link between changes in brain systems involved in reward and psychopathology and chronic cannabis abuse, suggesting a mechanism by which heavy use of this popular drug may lead to depression and other even more severe forms of mental illness," said Dr. Cameron Carter, Editor of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
These data and subsequent analysis suggest that different trajectories of adolescent cannabis use are associated with distinct patterns of neural reward circuit function in early adulthood. Escalating marijuana use presents a higher risk for impaired motivation, including elevated depressive symptoms, anhedonia and poor educational attainment. It follows that alterations, perhaps the degradations of the reward circuitry, represent the mechanism by which cannabis users fail to attain their potential, resulting in both developmental and dose-dependent impairment in their higher-level functioning.
Published: 28 November 2017
Cannabis use in young people is common and associated with psychiatric disorders. However, the prospective link between cannabis use and bipolar disorder symptoms has rarely been investigated. The study hypothesis was that adolescent cannabis use is associated with hypomania in early adulthood via several potential etiological pathways.
Results & Conclusions
Data were available on 3370 participants. Cannabis use at least 2–3 times weekly was associated with later hypomania (OR = 2.21, 95% CI = 1.49–3.28) after adjustment - Adolescent cannabis use may be an independent risk factor for future hypomania, and the nature of the association suggests a potential causal link. Cannabis use mediates the link between childhood abuse and future hypomania. As such it might be a useful target for indicated prevention of hypomania.