Prader-Willi syndrome and psychotic symptoms: report of a further case

A 21 year-old woman with Prader-Willi syndrome (PWS) and a delusional disorder (paranoid psychosis) is described. Other reports of psychoses associated with PWS are reviewed. Reasons for the co-existence of the two disorders are considered, with discussion of the possible role of auditory information processing deficits in the genesis of psychotic symptoms. Such symptoms must be differentiated from maladaptive behaviours not arising from psychosis, the latter being relatively common in PWS. Treatment with a small dose of flupenthixol greatly reduced the impact of the patient's psychotic symptoms, with a corresponding improvement in her quality of life.