Is a child's risk of early onset schizophrenia increased in the highest social class?

In a sample from the unselected, general population Northern Finland 1966 Birth Cohort, 11017 individuals alive at the age of 16 years were studied until the age of 27. The cumulative incidence of early onset schizophrenia until 23 years was higher (1.14%; 9/792) among young persons from the highest social class or class I (determined according to father's occupation) than among children from lower social classes (0.47%; 48/10225), the difference being statistically significant (p < 0.05). The incidence of schizophrenia in the highest social class was higher than expected among girls, firstborns, children of young mothers under 30 and urban residents (p < 0.05) compared with lower social classes. When cases from the highest and other social classes were compared, there was no clear difference in background factors or clinical course. Four alcoholics, one of them also schizophrenic, were found among nine social class I fathers. The results suggest that in some families in Northern Finland, a father's professional advancement, often linked to mental disorder, may be one determinant of an increased risk of schizophrenia in the child.