Objective: To calculate the incidence rates of hospital-treated psychosis and suicide in historical cohorts of a small rural community in southeast Norway, and to compare the local findings with the national ones.
Method: We have carried out a longitudinal epidemiological study, reviewing the patient records at the mental hospitals of people born in the rural community after 1845. Based on these records, we have constructed a local register of psychosis and suicide in this population. The local incidence rates of psychosis and suicide have been compared with the national ones.
Results: The overall local incidence rates of psychosis and suicide were similar to the national ones. The local rates of schizophrenia dropped considerably after World War II.
Conclusion: The overall local incidence rates of psychosis and suicide seem to be representative for the country at large despite frequent endogamy. The recent drop in the incidence rate of schizophrenia seems to be in agreement with several international studies.