The relationship between compulsive behaviour and academic achievement across the three genetic subtypes of Prader-Willi syndrome

Abstract

Background: Prader-Willi syndrome (PWS) is a genetic syndrome associated with several physical, cognitive and behavioural characteristics. For many individuals with this syndrome, compulsive behaviour is often noted in both food and non-food situations. The focus of this paper is on the non-food-related compulsions in individuals with PWS and comparing differences across the three genetic subtypes of the syndrome.

Methods: Compulsive behaviours in 73 people with PWS were assessed using the Yale-Brown Obsessive Compulsive Scale and the Compulsive Behavior Checklist. Compulsive behaviour and its relation to IQ and academic achievement also were evaluated. Phenotypic differences were characterized for the three most common genetic subtypes of the disorder: 16 individuals with the long Type I (TI) 15q deletion, 26 individuals with the short Type II (TII) 15q deletion and 31 individuals with maternal disomy 15.

Results: There appeared to be important differences between the two deletion subtypes. Specifically, individuals with the TI deletion had more compulsions regarding personal cleanliness (i.e. excessive bathing/grooming), and their compulsions were more difficult to interrupt and interfered with social activities more than the other subtypes. Individuals with the TII deletion were more likely to have compulsions related to specific academic areas (i.e. rereading, erasing answers and counting objects or numbers).

Conclusions: These findings may help clinicians and researchers identify possible intervention strategies and supports based on the behavioural phenotype associated with genetic subtype in individuals with PWS.

Figure 1

Chromosome 15 ideogram indicating the Type I and Type II deletion areas. BP, breakpoint.

Figure 2

Proportion of caregiver ratings (none, mild, moderate, or severe) by PWS subtype for three compulsions that were significantly different on the YBOCS (excessive bathing/grooming, counting and rereading/erasing). PWS, Prader–Willi syndrome; YBOCS, Yale-Brown Obsessive Compulsive Scale; TI, Type I; TII, Type II.

Figure 3

Proportion of caregiver ratings (none, mild, moderate, or severe) by PWS subtype for two areas of interference were significantly different on the CBC (compulsion interferes with social activities and compulsions takes more than an hour a day). PWS, Prader–Willi syndrome; CBC, Compulsive Behavior Checklist; TI, Type I; TII, Type II.

Figure 4

Proportion of caregiver ratings (never, rare, some, or often) by PWS sub-type for two areas of interference were significantly different on the CBC (becomes upset when compulsion interrupted and halts momentarily then resumes compulsive activity). PWS, Prader–Willi syndrome; CBC, Compulsive Behavior Checklist; TI, Type I; TII, Type II.