Lifetime duration of cannabis use, cognition linked in schizophrenia
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Key takeaways:
- There were positive associations between lifetime cannabis use and cognition in people with schizophrenia.
- The association was not causal.
SAN FRANCISCO — Among people with schizophrenia, lifetime duration of cannabis use was associated with cognitive function, according to a poster presented at the American Psychiatric Association annual meeting.
“There is some data that shows a positive association between THC and the development of schizophrenia, but the recent data with the cannabidiol specifically had some positive effects in terms of antipsychotic properties was particularly interesting to me,” Jeff Wang Jin, MD, who was a student at the University of Texas Health Science Center in Houston at the time of the study, told Healio. “I felt that was an avenue that should be explored more.”
Jin, now a resident physician at Dartmouth Health in New Hampshire, and colleagues conducted a cross-sectional study among 31 inpatients with schizophrenia at the Harris County Psychiatric Center in Houston. Participants completed the cannabis abuse screening test (CAST), the Kreek-McHugh-Schluger-Kellogg (KMSK) cannabis scale and the Montreal Cognitive Assessment (MoCA). These were used to evaluate associations between cognition and 30-day and lifetime cannabis use.
“We found strong positive associations between lifetime duration of cannabis use and cognition,” Jin told Healio.
Specifically, there were significant associations for MoCA abstraction (P = .021) and orientation (P = .003) scores. There were also positive associations between lifetime cannabis frequency and total MoCA scores, abstraction scores and orientation scores.
Analyses of 30-day cannabis use revealed a moderate association between duration of use and language MoCA scores, although the relationship was not significant upon further adjustment.
Notably, Jin said the relationship was not determined to be causal, and that the findings do not yet have clinical implications.
“The research that I would be more interested in is long-term [effects in patients with] schizophrenia and psychosis,” Jin said about future steps. “I think it would be better to track use of cannabis over time, as well as simplifying it down to knowing exactly what is in the cannabis itself — whether it is 100% THC, 100% CBD — and not having this mixture of things that we don’t know what exactly is in it, like in Houston where it’s not necessarily legalized yet.”