The association between schizophrenia and smoking: unexplained by either the illness or the prodromal period.

Age at onset of daily smoking (AODS) was compared in schizophrenia (N=258), mood disorders (N=166) and controls (N=381) to replicate a different AODS in schizophrenia patients, and to confirm that this is not necessarily explained by the prodromal period. The cumulative hazard curves for schizophrenia, mood disorders and controls were significantly different (p<0.001), even after controlling for gender and education (p<0.001). After excluding the patients who started smoking within 5 years of starting psychiatric medication, the cumulative hazard curve for schizophrenia patients was significantly different from that for ever-smoker controls (p=0.002), even after adjusting for gender and education (p=0.03).