Affective psychosis and Prader-Willi syndrome

Previous studies have demonstrated that maladaptive behaviours are common a mongst adults with Prader-Willi syndrome (PWS). Case reports have also prev iously demonstrated that psychosis can occur amongst adults with PWS. The p resent study was undertaken in order to gin a better understanding of the p sychopathology of the psychosis of PWS. Twenty-three out of 25 adults ident ified with PWS living in Northamptonshire, UK, agreed to participate. Compr ehensive psychiatric assessments (using the PPSLD), and measures of adaptiv e and maladaptive behaviours (using the AAMR-ABS) were completed. Compariso ns were made for the prevalence of psychiatric disorders against those from a previous epidemiological study of adults with intellectual disability of other aetiologies from a neighbouring county. The PWS group was found to h ave higher rates of affective disorders (a point prevalence of 17.4%), in w hich psychotic symptoms were common, but similar rates of schizophrenia/del usional disorders (4.3%) compared with the comparison group. Behaviour diso rders were also common. Surprisingly, none of the PWS group was found to ha ve generalized anxiety or phobic disorders. The diagnostic criteria for the episodes including psychotic symptoms are explored. The high rates of affe ctive disorders is of clinical (i.e. treatment) importance as well as being of academic interest with regard to the genetics of psychiatric disorders.