First-contact rate for schizophrenia in community psychiatric care. Consideration of the oestrogen hypothesis

The study deals with the incidence of schizophrenia in Finland. All patients aged 15 years and over who during 1 year for the first time in their life contacted any psychiatric treatment unit in six health care districts (catchment areas), with a total population of 1.1 million people, and suffered from schizophrenia as defined by the DSM-III (schizophrenic and schizophreniform disorders) or ICD-8 classifications were studied and followed for 5 years. A total of 186 DSM-III and 158 ICD-8 schizophrenia patients were registered. The incidence rate of DSM-III schizophrenia was 17 per 100,000 total population and that for ICD-8 schizophrenia 14 per 100,000. The incidence rates for individuals aged 22-34 years, singles and those with low education were higher than average, but there were no gender differences. The comprehensiveness of the psychiatric services may explain why the age distributions were similar for both genders and why the mean age of patients at their first psychiatric contact was lower than in many other studies dealing with hospitalized patients. The patients' age at first psychiatric contact did not support the view that oestrogens specifically delay the onset of schizophrenia in women. There is some evidence, however, that oestrogens as antidopaminergic agents may protect women from psychotic disorders in general and that the reduction in oestrogen production may explain why at menopause and afterwards admissions for psychotic disorders for women increase more than for men.