Long-term course and outcome in delusional disorder.

Out of 301 first-time admitted patients with delusional psychoses, 71 met Kendler's criteria of delusional disorder (DD) and 137 met the ICD-9 criteria of schizophrenia (S). DD was subdivided according to operational criteria into reactive delusional disorder (RDD) with precipitating factors (n = 31) and non-RDD (n = 40). At follow-up after 22-39 years, 20 RDD patients, 21 non-RDD patients and 85 S patients were personally interviewed. The delusions had faded in 61% of DD cases, were unchanged in 17%, and more prominent in another 17%. Recovery was recorded in 37%, mild defect in 32%, moderate impairment in 10%, and severe impairment in 22% of DD patients. Outcome was more favourable in DD compared with S, in RDD compared with non-RDD, and in non-RDD compared with S. The study supports distinctions between DD and S, RDD and non-RDD, and non-RDD and S based on course and outcome.