Background: Although neurological soft signs (NSS) have been consistently associated with schizophrenia and a variety of risk factors, few studies have focused on the association between NSS and environmental factors such as cannabis use, particularly in patients with first episode psychosis.
Methods: We administered the Neurological Evaluation Scale (NES) to 92 patients during their first episode of functional psychosis. Psychopathology was assessed with the Positive And Negative Syndrome Scale (PANSS) and the family history of psychotic disorder was established on the basis of the Family Interview for Genetic Studies (FIGS). We also assessed lifetime cannabis and cocaine use utilizing that specific section of the Composite International Diagnostic Interview. The outcome variable was the presence of high NSS, defined by a score above the median split of the NES score (>21).
Results: Most patients (80/92, 87%) presented a non-affective psychosis. The presence of high NSS showed a significant independent association with not having been a heavy cannabis user (OR=8.3; 95% CI, 2.4-33.3), family history of psychosis (OR=4.3; 95% CI, 1.2-14.9), male sex (OR=4.0; 95% CI, 1.2-14.0), lower score in verbal fluency and higher score in negative symptoms (both p<0.01).
Conclusion: Our cross-sectional results support the hypothesis that potentially different pathways associated with the emergence of first episode psychosis may exist, including neurological premorbid alteration and environmental cannabis abuse.