Schizophrenia patients who have a history of cannabis use show a different brain activity pattern in an fMRI than schizophrenics without prior cannabis use, according to a study published in Frontiers in Psychiatry.

The finding came from a team at the University of Bergen in Norway who demonstrated in a previous report that cannabis use leads to a temporary cognitive breakdown in non-psychotic people, eventually resulting in long-term psychosis. A report from Yale researchers also indicated that the main active ingredient in cannabis causes temporary schizophrenia-like symptoms, such as delusions to impairments in memory and attention.

The new results provide evidence that cannabis users who are struggling with schizophrenia may surprisingly have higher cognitive abilities than schizophrenics who do not use cannabis. According to the authors, this mays suggest that those who used cannabis did not have the same mental inclination for psychosis.

Else-Marie Loeberg, lead author and associate professor of Psychology at the University of Bergen, Norway, said:

“While brain activity for both groups was similar, there are subtle differences between schizophrenia sufferers with a history of cannabis use and those who have never used cannabis. These differences lead us to believe that the cognitive weakness leading to schizophrenia is imitated by the effects of cannabis in otherwise non-psychotic people.”

The study consisted of 26 patients who were asked to try complicated cognitive tasks while in the fMRI machine. The subjects heard different syllables in each ear and were asked to say which one they heard when they were told to focus on either the left or right ear.

Since this assignment is rather challenging for anyone, it is especially hard for people suffering with schizophrenia because they often have:

  • difficulty in processing verbal cues
  • impaired attention
  • limited executive functioning

The experts found that schizophrenia patients with a history of cannabis use not only had consistently higher levels of brain function while taking tests, but they also answered a greater number of questions correctly.

This study supports the team’s theory that cannabis users who have schizophrenic qualities do not experience with the same nuero-cognitive shortcomings as other schizophrenia sufferers.

This suggests, according to the authors, that otherwise non-psychotic people are guided in the direction towards schizophrenia by cannabis use alone, because it mimics the cognitive defect that is the primary risk factor for developing the disorder.

Written by Sarah Glynn