according to a study published online in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
Researchers from the National Institute on Alcohol Abuse and Alcoholism in Bethesda, Maryland, reached the finding after assessing resting-state brain activity data for 441 young adults from the Human Connectome Project then comparing 30 of them, who met DSM-IV criteria for cannabis dependence, with 30 matched control subjects.
Heavy cannabis use, they found, was associated with abnormally high connectivity in brain regions linked with habit formation and reward processing. Previous research has implicated the same regions in the development of psychosis, researchers pointed out.
In addition, brain alterations were linked with increased negative emotionality and feelings of alienation, according to the study, which could explain why alienation is commonly reported by people with cannabis dependence.
“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 Cameron Carter, MD, Biological Psychiatry editor.