Acute polymorphic psychotic disorder: diagnostic stability over 3 years

Objective:  Acute polymorphic psychotic disorder without symptoms of schizophrenia (APPD) in ICD‐10 is unique in many characteristics. This study aimed at investigating the diagnostic stability of APPD over 3 years. Method:  Forty‐five patients with first episode APPD were followed up and assessed at regular intervals over a period of 3 years. Results:  Thirty‐two patients were females. Average age of the sample was 26.9 years. Thirty‐three cases retained their index diagnosis of APPD, while 12 cases required diagnostic revision: 10 to bipolar affective disorder and the rest to unspecified non‐organic psychosis. Shorter duration of illness (<1 month) and abrupt onset (<48 h) predicted a stable diagnosis of APPD. Conclusion:  APPD is a relatively stable diagnosis and argues for a distinct diagnostic entity.