Cannabis Use Linked to Better Social Skills in Psychosis

Liam Davenport

March 21, 2016

MADRID — Psychosis patients who have used cannabis have greater premorbid social skills than patients with psychosis who have never used the drug, data from five European countries suggest.

Laura Ferraro, a PhD student in psychiatry at the University of Palermo, in Italy, and colleagues found that lifetime cannabis use was associated with significantly increased improvements in premorbid social adjustment among psychosis patients.

Moreover, the results, which were presented here at the European Psychiatric Association (EPA) 24th ​Congress, indicate that the impact of cannabis on sociability was significantly greater among psychosis patients than among healthy individuals.

Ferraro said that psychotic patients who consume cannabis are thought to represent a distinct subgroup with better cognitive and social skills, which "is necessary to engage in illegal drug consumption." Moreover, a previous study by Ferraro and colleagues showed that among patients with first-episode psychosis (FEP), those who used cannabis had a higher IQ.

Noting that the prevalence and patterns of cannabis use are culturally driven, the researchers examined data from the EU-GEI project, which includes FEP patients and healthy control individuals from France, Italy, the Netherlands, Spain, and the United Kingdom.

The sample included 746 FEP patients and 999 healthy control persons, all of whom completed the premorbid adjustment scale (PAS) and the Cannabis Expectancy Questionnaire–Revised.

The team extracted the premorbid social adjustment factor from the PAS, on which a lower score shows greater sociability. A linear mixed model was then performed in which PSA was the dependent variable and lifetime cannabis use (yes/no) and status (case/control) were the independent variables.

Taking into account age and sex, the team found that, across all countries, PSA scores were significantly better among patients who had ever smoked cannabis than those who had not (P = .009).

Furthermore, the difference in PSA scores between ever cannabis users and nonusers was significantly higher among patients than in control persons, demonstrating an interaction effect (P = .038).

Examining the results by country yielded similar results, with notable differences in mean PSA scores between ever cannabis users and nonusers. However, PSA scores in both groups were lower in Spain than in the other countries, prompting Ferraro to add: "Congratulations to Spain. That is the most sociable country in Europe!"

Ferraro concluded that future directions for the research include repeating the analysis in a larger sample, across the entire EU-GEI dataset, as well as investigating patterns of cannabis use, diagnosis, and tobacco smoking.

Another avenue for investigation would be to develop a model that includes both premorbid academic adjustment and IQ, which might help "explain these counterintuitive findings."

Not Causal

Commenting on the study, William T. Carpenter Jr, MD, professor of psychiatry and pharmacology at the University of Maryland School of Medicine, in Baltimore, told Medscape Medical News that the findings are "expected, and no doubt correct." He added that few scientists would interpret the better cognition associated with cannabis use in schizophrenia as a causal relationship.

He explained that the early onset of negative symptoms and cognitive impairment "creates reduced social networks and interactions and a reduced anticipated pleasure for shared activities.

"Consequently, an individual with early social and cognitive impairments is, for several reasons, less likely to be a cannabis user."

The authors and Dr Carpenter report no relevant financial relationships.

European Psychiatric Association (EPA) 24th Congress: Presented March 14, 2016.


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