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Smoking marijuana can lead to schizophrenia
Last reviewed: 01.07.2025
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Researchers from the University of Bergen in Norway have found that cannabis use causes temporary non-psychotic cognitive impairment leading to long-term psychosis.
Using magnetic resonance imaging, the researchers found that brain activity in patients with schizophrenia who had previously used cannabis differed from the brain activity of similar patients without cannabinoid addiction.
The results support the researchers' theory that cannabis-using schizophrenia patients may actually have higher cognitive abilities than those who have never used the drug. This difference may indicate that the propensity for psychosis in cannabis-dependent schizophrenics is different from the general population.
"These differences suggest that cannabis mimics the cognitive impairment that causes schizophrenia in mentally healthy individuals," explains Marie Loberg, lead author of the study.
The 26 patients in the study attempted to solve complex problems while experts performed magnetic resonance imaging (MRI) scans on them. For example, the doctors spoke different syllables into each ear at the same time and asked the patients to focus on one of the sounds and then reproduce it. This is a difficult task for anyone, but it is doubly difficult for people with schizophrenia, who suffer from impaired attention and concentration, and have difficulty processing verbal signals.
The study shows that schizophrenia patients with previous cannabis use were consistent and had higher levels of brain activity while taking these tests, as well as a higher number of correct answers.
The findings are consistent with the findings of the Bergen researchers, who support the idea that cannabis-dependent people with schizophrenia disorder do not seem to suffer from the same neurocognitive impairments as other patients with schizophrenia.
This means that cannabis use leads non-psychotic individuals to schizophrenia by mimicking the cognitive weakness that is a major risk factor for developing the psychological condition.
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