Impact of cannabis use in patients with schizophrenia- a cross sectional comparative study

Abstract

Background: Cannabis has become one of the key substances attracting increasing attention in recent times, particularly for its association with psychotic disorders. Neurological soft signs (NSS) are subtle motor and sensory integration abnormalities observed in schizophrenia, reflecting underlying neurodevelopmental dysfunction. Cannabis use is increasingly prevalent in schizophrenia and may influence the clinical and neurobiological phenotype, including NSS. Aim: To compare NSS and psychopathology in schizophrenia patients with and without cannabis use. Materials and methods: A comparative cross-sectional study was conducted among 60 male patients diagnosed with schizophrenia (DSM-5 criteria), divided equally into two groups: those with (n = 30) and without (n = 30) cannabis use. Cannabis use of more than 2 years’ duration was confirmed using the Cannabis Use Disorder Identification Test–Revised (CUDIT-R) and the Severity of Dependence Scale (SDS). The Neurological Evaluation Scale (NES), Scale for the Assessment of Positive Symptoms (SAPS), Scale for the Assessment of Negative Symptoms (SANS), and Brief Psychiatric Rating Scale (BPRS) were administered. Statistical analysis was performed using SPSS v26.0. Results: Cannabis users showed significantly lower scores in the NES domain “sequencing of complex motor acts” (p = 0.042), suggesting better motor coordination. No significant differences were observed in total NSS or other subdomains. Cannabis users had significantly higher SAPS (p = 0.036) and BPRS scores (p = 0.014) and lower SANS scores (p = 0.010), indicating greater positive symptoms, overall psychopathology, and lesser negative symptoms. Among users, the mean CUDIT-R score was 6.26 ± 7.32, and the SDS score was 3.16 ± 3.52. Half of the users initiated cannabis between ages 16 and 20, and 43.4% used it weekly. Conclusion: Schizophrenia patients with cannabis use exhibited milder deficits in certain NSS domains and a higher positive symptom burden. These findings suggest a distinct clinical profile and possible neurodevelopmental variation, underlining the importance of screening for cannabis use.