The Zurich Study. VI. A continuum from depression to anxiety disorders?

A representative sample of 456 persons from the normal population aged 22 and 23 years was used to study the overlap of depression with anxiety disorders. The 1-year prevalence rate for major depression (DSM-III), minor depression, and anxiety disorder together was 16.4%. The observed cases of major depression occurred in 36% with anxiety disorder, the cases with minor depression in 60%. On the level of symptoms assessed by a semistructured clinical interview and on the level of self-assessed items of the symptom check list SCL-90, the overlap was even greater. The main finding was that subjects with both diagnoses, depression and anxiety disorder, were more severely affected in general. Discriminant analyses of the SCL-90 scales together with the qualitative distribution of SCL items characterizing depression, anxiety, or phobia, did not disprove the hypothesis of a continuum.