Table 1.
Demographic characteristics of the schizophrenia (SZ) sample.
| Number of individuals, N (%) | 1,219 (100) |
| Gender, male, N (%) | 857 (70) |
| Age at interview, mean (SD) | 42.68 (9.46) |
| Age of onset of schizophrenia, mean (SD) | 21.21 (7.58) |
| Ethnicity, Caucasian, N (%) | 1,219 (100) |
| Positive family history of psychosis, N (%) | 378 (31) |
| Individuals with | |
| drug and alcohol related disorders, N (%) | 664 (54) |
| alcohol abuse, N (%) | 200 (17) |
| alcohol dependence, N (%) | 310 (26) |
| cannabis abuse, N (%) | 422 (35) |
| illegal substance abuse, N (%) | 161 (13) |
| illegal substance dependence, N (%) | 169 (14) |
| major depressive disorder1, N (%) | 256 (21) |
| drug and alcohol abuse before onset of SZ, N (%) | 432 (36) |
| drug and alcohol abuse after onset of SZ, N (%) | 232 (18) |
1
according to DSM-IV