Age of initiation of regular smoking and age of onset of psychiatric disorder among men and women according to diagnostic subgroup in the Northern Finland 1966 Birth Cohort
| Diagnostic group | Total (n = 10 934) | Subjects for whom data about smoking were available (n = 8324) | ||||||
|---|---|---|---|---|---|---|---|---|
| No. | Mean age of onset of disorder (and SD), yr | No. | No. of smokers† | Mean age of onset of disorder (and SD), yr | Mean age of initiation of regular smoking (and SD), yr | Mean difference between ages of onset (and SD), yr‡ | p value§ | |
| Men | ||||||||
| Healthy control subjects* | 5276 | — | 3827 | 1318 | — | 17.7 (4.0) | — | — |
| Schizophrenia | 65 | 22.2 (3.9) | 40 | 22 | 20.9 (3.4) | 18.8 (4.5) | 2.2 (6.5) | Ref |
| Other psychoses | 26 | 24.1 (4.6) | 19 | 9 | 24.7 (4.3) | 16.0 (4.4) | 8.7 (7.9) | 0.015 |
| Nonpsychotic disorders | 222 | 23.3 (4.1) | 112 | 63 | 23.7 (4.1) | 15.9 (3.8) | 7.8 (4.7) | < 0.001 |
| Women | ||||||||
| Healthy control subjects* | 5188 | — | 4214 | 925 | — | 18.5 (4.2) | — | — |
| Schizophrenia | 35 | 22.1 (4.1) | 27 | 8 | 23.9 (3.3) | 21.2 (5.7) | 2.6 (6.2) | Ref |
| Other psychoses | 29 | 25.7 (4.3) | 20 | 9 | 25.8 (4.8) | 17.3 (4.4) | 8.4 (4.7) | 0.13 |
| Nonpsychotic disorders | 93 | 24.6 (4.6) | 65 | 25 | 23.4 (5.1) | 19.9 (5.7) | 3.5 (5.9) | 0.94 |
Note: SD = standard deviation.
↵* These subjects had no psychiatric disorder.
↵† Not included in this column are smokers for whom the age of onset of smoking was missing, namely, 2 female subjects with schizophrenia, 5 men and 5 women with nonpsychotic disorders and 58 men and 68 women without psychiatric hospital treatment.
↵‡ Mean difference (and SD) between age of onset of psychiatric disorder and age of onset of regular smoking.
↵§ Analysis of variance with Scheffé’s multiple comparison test: comparison of mean difference in ages of onset between subjects with schizophrenia (ref) and other diagnostic groups among smokers.