Relationship between cannabis use, schizotypal traits, and cognitive function in healthy subjects.

This research examined the relationship between cannabis use and schizotypal features. A sample of cannabis users (n = 20) was compared with a matched control group (n = 20). All participants were male students of the University of Hamburg. Subjects completed the Perceptual Aberration Scale and the Schizotypal Personality Questionnaire. A Negative Priming procedure and the Trail Making Test were carried out. A urine sample was obtained from each subject. Cannabis users exceeded controls in schizotypy scores and showed impaired neuropsychological parameters. Only within the cannabis group schizotypy scores correlated with neuropsychological parameters. Furthermore, cannabis users reported more often high-risk factors than controls. These findings indicate that among cannabis users there is an increased number of subjects with schizotypal features; schizotypal subjects seem to be more likely to use cannabis than the general population. Therefore, cannabis use may be a vulnerability indicator for schizophrenia.