Changing trends in first admissions and readmissions for mania and schizophrenia in New Zealand, 1974 to 1984.

From 1974 to 1984 in New Zealand there was a significant decline in first psychiatric admissions for the functional psychoses. This decline is due to decreasing first admission rates for schizophrenia and depressive psychoses, despite an increasing first admission rate for mania. Although a small part of the declining first admission rate for schizophrenia may be due to the increasing diagnosis of mania, this is insufficient to explain all the decline and suggests an actual decline in the incidence of schizophrenia. Over this same period readmissions for functional psychoses increased, with the most marked increase being in manic readmissions. Although a variety of factors influence readmission rates, the marked rise in manic readmissions suggests broadening diagnostic criteria for mania.