The duration criteria of delusional disorder in modern classification.

This article briefly reviews the duration criteria for delusional disorder in current diagnostic systems. Furthermore, a sample of 72 first-admitted patients with delusional disorder, personally re-examined after a mean of 10 and 27 years, has been analysed as to duration of delusional symptoms. One third of the sample displayed delusions for less than 6 months at admission. During the observation period one half of these patients (one sixth of the total sample), displayed delusional symptoms for less than 6 months, recovered fully, and functioned excellently at follow-up, while patients with a total duration of delusions for more than 6 months functioned worse. This report adds further support to setting up a dividing line of 6 months for the separation of acute from persistent delusional disorder.