Cannabis Changes Brain Structure

The brain has two parts: gray matter and white matter. The gray matter refers to the nerve cells of the brain, and the white matter refers to the cables that connect those nerve cells.

The two structures where differences occur are hippocampus and the amygdala. The hippocampus is an important structure of the brain for learning and memory. Every time we learn or recall about facts we use that structure. The amygdala is part of the limbic system responsible for processing emotions.

Cannabis use in psychosis is associated with volume loss of global and specific brain structures, whereby the effects seem to be particularly strong in CB1 rich brain regions such as the cingulum, the dorsolateral prefrontal cortex and the cerebellum. Psychosis patients and subjects at risk for psychosis might be particularly vulnerable to brain volume loss due to cannabis exposure.

Brain damage

Substance abuse is the most prevalent psychiatric condition associated with schizophrenia, and cannabis is the illicit drug most often abused. Apart from worsening the course of schizophrenia, frequent cannabis use especially at an early age seems to be an important risk factor for developing schizophrenia. Volume loss is occurring in gray matter, the very structure shown to be particularly susceptible to the effects of alcohol and cannabis in dual diagnosis studies of schizophrenia. The consequences of this brain tissue loss in adolescents at high risk of developing schizophrenia appear to be profound, this being reflected in the elevated risk of psychosis in those individuals with a history of either alcohol dependence or substantial exposure of cannabis.


  1. Effects of Cannabis Use on Human Brain Structure in Psychosis: A Systematic Review Combining In Vivo Structural Neuroimaging and Post Mortem Studies
  2. he Impact of Substance Use on Brain Structure in People at High Risk of Developing Schizophrenia



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