Background: Recent research suggests that high familial loading is associated with early onset of schizophrenia. Results concerning outcome have been controversial.
Method: We assessed the relationship between familial loading, age at onset and outcome in all Finnish patients with schizophrenia born between 1950 and 1969. Patients and their first-degree relatives were identified using nationwide registers. Familial loading scores were calculated for schizophrenia and for combined psychotic disorders, and patients were accordingly classified into three groups: high (n = 761), intermediate (n = 14,247), and low familial loading (n = 725). Linear mixed models and the Cox proportional hazard model were used in the analyses.
Results: Onset was earliest, hospitalisation longest and risk of retirement in receipt of a disability pension highest in the group with high familial loading, with opposite extremes found in the group with low familial loading.
Conclusions: High familial loading for schizophrenia is associated with early onset and poor outcome of schizophrenia.