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Abstract
Aim
Cannabis use is common in people with psychotic disorders. However, the effect of cannabis on cognition in psychosis remains unclear. Our study investigates relationships between the history of cannabis use and cognitive performance in patients with first-episode psychosis (FEP) during a one-year follow-up.
Methods
The present study included FEP (N = 91) and control (N = 61) groups. Cannabis use was evaluated with a self-report questionnaire, clinical assessment, and medical records during a lifetime and 12 months prior to the treatment onset (recent). Symptoms of psychosis and anxiety were evaluated on the brief psychiatric rating scale. Negative symptoms were assessed using the scale for the assessment of negative symptoms. Cognitive tests were used to evaluate neurocognition (summarized in the g factor) and social cognition. Crude regression analyses for the g factor included variables of cannabis use as independent variables. Full regression models were controlled for gender, education, and clinical symptoms.
Results
In the FEP group, men used cannabis more frequently than women. In the crude regression model for FEP patients, never having used cannabis was associated with a better neurocognitive profile at 12 months. In the full model, more severe anxiety symptoms were associated with better neurocognition at two months, and less severe negative symptoms were associated with better neurocognition at 12 months. Cannabis use was not associated with social cognition. No associations between cognitive performance and cannabis use emerged in the controls.
Conclusion
Negative and affective symptom severity in FEP was associated with cognitive performance to a greater degree than a lifetime history of cannabis use.
Acknowledgments
The authors thank Marjut Grainger, Laura Hietapakka, Sanna Järvinen, Tuula Mononen, Teemu Mäntylä, Eva Rikandi, Sebastian Therman, and all the participants in the study.
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Funding
Notes on contributors
Boris Karpov
Boris Karpov, MD, PhD, Helsinki University Hospital. He works as a Head Physician at the Clinic for Psychotic disorders and Forensic Psychiatry at the Helsinki University Hospital. He does research in comorbidity of mental disorders and first-episode psychosis.
Maija Lindgren
Maija Lindgren, PhD (psychology), Adjunct Professor (title of docent), University of Helsinki. She works as a Research manager at the Finnish Institute for Health and Welfare, Finland. She does research in psychosis risk, psychotic-like experiences, first-episode psychosis, and cognitive functioning.
Tuula Kieseppä
Tuula Kieseppä, MD, PhD, Adjunct Professor (title of docent), University of Helsinki. She works as a Chief Medical Doctor at the Ministry of Social Affairs and Health, Finland. She does research in severe mental disorders and first-episode psychosis.
Asko Wegelius
Asko Wegelius, MD, PhD, Helsinki University Hospital. He works as a Head Physician at the Clinic for Psychotic disorders and Forensic Psychiatry at the Helsinki University Hospital. He does research in schizophrenia and first-episode psychosis, as well as sleep disorders.
Jaana Suvisaari
Jaana Suvisaari, M.D., Ph.D., is research professor at the Finnish Institute for Health and Welfare. Her research focuses are (1) psychotic disorders, from etiological mechanisms to early detection, treatment and outcome prediction, (2) general population-based research on mental health and (3) mental health services. She has published over 300 articles.