Compulsive behavior in Prader-Willi syndrome: examining severity in early childhood.

Prader-Willi syndrome (PWS) is a genetic disorder characterized by hyperphagia and food preoccupations. Researchers indicate that individuals with PWS, including young children, exhibit food and non-food-related compulsions. Normative rituals are also often present among typically developing preschoolers. However, it is unclear how these behaviors affect the child. Although preschoolers with PWS exhibit more types of rituals than other populations, it is uncertain if the severity of these behaviors differs from the rituals experienced during normative development. Thus, the purpose of this research was to determine whether the ritualistic behaviors exhibited by preschoolers with PWS differ in severity from those exhibited during normative development. We also sought to identify whether non-food ritualistic behavior was related to the hyperphagia in PWS. Parents of 68 children with PWS, 86 typically developing children, and 57 children with developmental delays completed questionnaires on rituals and eating behavior. Children with PWS exhibited more severe ritualistic behavior than typically developing children but not other children with developmental delays. However, the severity of non-food-related rituals was related to the severity of eating behavior in PWS. We hypothesize that this link between hyperphagia and non-food-related compulsivity may share a common underlying neurobiological mechanism.

Emergence of compulsive behavior and tantrums in children with Prader-Willi syndrome.

Many adults with Prader-Willi syndrome are affected by behaviors such as tantrums, skin-picking, and compulsions. The nature and extent of these problems suggest more attention be directed to their emergence in childhood. Our purpose was to investigate behavior problems in children with this syndrome and identify the age at which these behaviors emerge. Parents of children with Prader-Willi syndrome, Down syndrome, and those developing typically completed questionnaires. Children with Prader-Willi syndrome exhibited more compulsions, skin-picking, and tantrums than did the other groups. A discriminant analysis of behavior variables derived two statistically significant functions that were interpreted as developmental milestones and problematic behavior. These functions correctly predicted membership for 79% of grouped cases.

The latent variable structure of the Compulsive Behaviour Checklist in people with Prader-Willi syndrome.

The presence and severity of compulsive behaviours may be evaluated via the Compulsive Behaviour Checklist (CBC) and this instrument has been successfully employed in people with intellectual disability. However, the applicability of the overall CBC scoring system, which entails tallying the number of behavioural categories represented (i.e. five) as well as the number of individual behaviours endorsed (i.e. 25), is not known in the population with Prader-Willi syndrome (PWS). The present investigation examined the latent variable structure of the CBC in people with PWS in order to identify possible population-specific scoring and interpretation considerations. The 25 behaviour-specific items of the CBC were analysed for 75 people with PWS (44 females and 31 males) aged between 4 and 41 years (mean +/- SD = 11.4+/-9.4) via factor analysis with principal component extraction and equamax rotation. The most suitable solution was determined on the basis of multiple empirical criteria: (1) the scree test; (2) eigenvalues >1.00; (3) salient loadings >0.30; (4) the clarity of item assignment to a single latent dimension; (5) the internal consistency of the latent dimension(s) (coefficient alpha > or = 0.70); and (6) item-total correlations between 0.20 and 0.79. In addition, solutions were examined with respect to psychological theory and previous research. A 'general factor' (i.e. single latent dimension) solution which adhered to all a priori criteria was indicated. Twenty-four out of 25 items achieved salient loadings ranging from 0.46 to 0.80 on the general factor. The single item which failed to achieve salience, 'deviant grooming-skin picking', exhibited both substantial unique variance (0.997) and moderate reliability (r = 0.59, P<0.001). The internal consistency of the general factor was strong (alpha = 0.93) and all salient items were suitably correlated with the unit-weighted total score (r(item-total) = 0.41-0.77). The traditional CBC scoring system, which includes tallying the number of categories represented, would not be relevant in this PWS sample. In addition, the recommended tallying of the number of individual behaviours endorsed does not reflect the empirically indicated notion of compulsive behaviour in this special population. These findings indicate that the 24 salient items should be scored as a unit-weighted composite and that the score on the substantially unique item (skin picking) should be considered a separate measure when evaluating compulsive behaviours via the CBC in people with PWS.

Appetitive behavior, compulsivity, and neurochemistry in Prader-Willi syndrome.

Advances in genetic research have led to an increased understanding of genotype-phenotype relationships. Excessive eating and weight gain characteristic of Prader-Willi syndrome (PWS) have been the understandable focus of much of the research. The intense preoccupation with food, lack of satiation, and incessant food seeking are among the most striking features of PWS. It has become increasingly clear that the behavioral phenotype of PWS also includes symptoms similar to obsessive compulsive disorder, which in all probability interact with the incessant hunger and lack of satiation to engender the intense preoccupation and food seeking behavior that is characteristic of this disorder. Several lines of evidence suggest that genetic material on chromosome 15 may alter synthesis, release, metabolism, binding, intrinsic activity, or reuptake of specific neurotransmitters, or alter the receptor numbers and/or distribution involved in modulating feeding. Among the likely candidates are GABAnergic, serotonergic, and neuropeptidergic mechanisms. This review summarizes what is known about the appetitive behavior and compulsivity in PWS and discusses the possible mechanisms underlying these behaviors. MRDD Research Reviews 2000;6:125-130.