Ruminative thinking. A distinctive sign of melancholia.

We propose that ruminative thinking, the tendency to dwell on the same thought or theme, is useful for distinguishing melancholic from nonmelancholic major depression. We demonstrate that the symptom can be rated reliably and that interview ratings are concordant with ward observation of the symptom. The frequency of ruminative thinking, rated retrospectively in a prior study, was 60% in 75 patients having autonomous depression while only 18% of 48 nonautonomous patients were so affected. In this study, we found that ruminative thinking, prospectively rated in 71 patients with unipolar major depression, was present in 53% of patients with DSM-III melancholia but only 11% of the nonmelancholic patients. The presence of ruminative thinking appears to be useful for making the diagnosis of melancholia and its definition may facilitate study of the psychobiology of this disorder.