Results. 37, 8% patients had lifetime drug dependence (including alcohol and others drugs except for tobacco). The prevalence of dependence for the different drugs were: opioids 9, 8%, cocaine 11%, alcohol 29, 3%, cannabis 24, 4%, tobacco 68, 3%, caffeine 15, 9%. Drug dependent had more family and legal problems. At the multiple regression analysis it was observed that cannabis and tobacco dependence was associated with a decrease in the PANSS negative symptoms subscale, and on the contrary, alcohol dependence produces a similar intensity increase at that scoring. We don’t detect any clinical relevance effects over positive symptoms.

Conclusions. Cannabis and tobacco may improve schizophrenia negative symptoms or neuroleptic secondary effects or patients with few negative symptoms may have more predisposition to the use, on the contrary alcohol use can impairment those symptoms.