Persistence of the decline in the diagnosis of schizophrenia among first admissions to Scottish hospitals from 1969 to 1988.

Age-standardised rates were calculated for first admissions to hospital in Scotland with ICD-9 diagnoses of schizophrenia, affective psychoses, paranoid psychoses, reactive psychoses and depressive neuroses (ICD-9 295, 296, 297, 298 and 300.4) for the period 1969-88. First-admission rates for schizophrenia declined by an average of 3.3% per year in males and 4.4% per year in females over the period. The first-admission rate in males in 1988 was 8.4/100,000 (57% of 1969 rate) and in females was 4.8/100,000 (43% of 1969 rate). Rates for depressive neuroses, affective psychoses, reactive psychoses and combined psychoses also fell. Rates for mania rose, as did those for paranoid states in males. The decrease in first-admission rates is likely to reflect a true decrease in the incidence of schizophrenia over the period. The decline was unlikely to be accounted for by diagnostic change because there was no reciprocal increase in any other diagnosis sufficient to account for the change, and the rates for combined psychoses also decreased. There was evidence that rates for schizophrenia declined to a greater extent in younger age groups, especially in females. This could imply the presence of a birth cohort effect.