In March 2019 researchers from Spain published the results of their study to assess the effect of cannabis use on psychopathology, cognition and real-world functioning in schizophrenia-related disorders. A total of 123 clinically stable individuals (average age 41 years; 67% male; 67% single) with a schizophrenia-related disorder (average length of illness 14 years) were included in the study. Information on cannabis use was self-reported, for both life-time use and in the last year. This showed that 54% were lifetime cannabis users and 9% last year users. Results showed that lifetime cannabis users had more hospitalizations which started at a younger age than non-cannabis users. In addition, lifetime cannabis users had better cognitive functioning with better working memory and processing speed but worse real world social functioning than non-cannabis users. Individuals who had used cannabis for the last year initially appeared to have a worse mood (state of mind) but this association disappeared when medication was taken into consideration.
Menendez-Miranda I et al. History of Lifetime Cannabis Use Is Associated with Better Cognition and Worse Real-World Functioning in Schizophrenia Spectrum Disorders. Eur Addict Res. 2019 Mar 21;25(3):111-118.