Associations between early development and outcome in schizophrenia--A 35-year follow-up of the Northern Finland 1966 Birth Cohort

Delayed neuromotor development carries an increased risk of developing schizophrenia, and some authors have assumed that risk factors for schizophrenia such as delayed development are also prognostic indicators for patients with established illness. In those who do develop schizophrenia, it is not clear if these same early developmental markers influence the outcome of illness. Our aim was to examine the association between infant developmental milestones and a range of outcomes in patients with schizophrenia. Our sample was drawn from Northern Finland 1966 Birth Cohort and included 109 subjects for whom prospectively collected information on age of learning to stand, walk and talk was available and who had developed schizophrenia by the age 35 years. By utilizing national registers we examined outcomes related to service utilization, educational achievement, and occupational status. Age of illness onset was also analyzed. Based on the diagnostic interview, a subgroup of 59 cases was assessed in clinical examinations on functioning and quality of life. Contrary to a widespread assumption within the field of schizophrenia research, later attainment of developmental milestones was not associated with poor outcome. We conclude that risk factors for schizophrenia are not necessarily prognostic factors.