Decreasing rates of first-admission diagnoses of schizophrenia among females in Denmark 1970-84.

In Denmark age-standardized rates of first-admission diagnoses of schizophrenia in females decreased significantly by 44% from 1970 to 1984. The slope of the regression line is -0.21 per 100,000 female inhabitants aged 15 years or more per year. All age groups, but especially the age group 45-54 years, contributed to the decrease in rates. Coinciding with the decrease in schizophrenia rates, an increase in age-standardized rates of borderline states in the age group 15-44 years occurred. The slope of the regression line is +0.53 per 100,000 per year. The results are compared with those in males and possible causes of the decrease are discussed. There is every probability that, as in males, part of the decrease is due to changes in diagnostic habits.