Acute polymorphic psychosis in adults with mild intellectual deficits

Abstract This paper describes two representative cases of acute polymorphic psychotic disorder (APPD) defined in the International Classification of Diseases (ICD)-10 in adults with mild intellectual deficits. The patients showed mild intellectual impairment but had worked diligently for many years without their impairment being noticed by others. Some displayed maladjustments in their childhood and were classified as having intellectual disabilities. With their low self-esteem, precipitating events forced the patients to act inappropriately and, as a result, they became psychotic. Although APPD is supposed to occur without causative stress, an intellectual limitation combined with a certain personality can precipitate such a psychosis. It is noted that APPD might mask intellectual deficit and their precipitating factors and that a relapse could be prevented by advising a member of the patient's family.