A neuropsychological assessment of frontal cognitive functions in Prader-Willi syndrome

• Published in: Journal of intellectual disability research 2007-05, Vol.51 (5), p.350-365
• Main Authors: Jauregi, J., Arias, C., Vegas, O., Alén, F., Martinez, S., Copet, P., Thuilleaux, D.
• Format: Article
• Language: English
• Subjects: Achievement; Adolescent; Adult; Adult and adolescent clinical studies; Attention; Autism; Behavior disorders; Behavior Patterns; Behavior Problems; Biological and medical sciences; Body Composition; Body Mass Index; Cognition & reasoning; Cognition Disorders - diagnosis; Cognition Disorders - epidemiology; Cognition Disorders - physiopathology; Cognitive Ability; Cognitive Processes; cognitive profile; Comparative Analysis; Complex syndromes; Developmental disabilities; Evaluation Methods; Executive Function; Female; frontal functions; Frontal Lobe - physiopathology; Genetic disorders; Genetics; Humans; Intelligence; Intelligence Quotient; Male; Medical genetics; Medical sciences; Memory; Memory Disorders - diagnosis; Memory Disorders - epidemiology; Memory Disorders - physiopathology; Mental Retardation; Middle Aged; neuropsychological assessment; Neuropsychological Tests; Neuropsychology; Organic mental disorders. Neuropsychology; Patients; Personality Traits; Pervasive Developmental Disorders; Phenotypes; Prader-Willi syndrome; Prader-Willi Syndrome - epidemiology; Prader-Willi Syndrome - genetics; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Semantics; Severity of Illness Index; Short Term Memory; Social Behavior; Social behaviour; social cognition; Symptoms (Individual Disorders); Wechsler Adult Intelligence Scale; Withdrawal (Psychology)
• ISSN: 0964-2633; 1365-2788
• DOI: 10.1111/j.1365-2788.2006.00883.x

Background  Prader–Willi syndrome (PWS) is associated with a characteristic behavioural phenotype whose main features are, alongside compulsive hyperphagia, deficits in social behaviour: social withdrawal, temper tantrums, perseverative speech and behaviour, mental rigidity, stereotyped behaviour, impulsiveness, etc. Similar symptoms may also be found in autistic spectrum disorders and lesional pathologies of the frontal lobe. In both cases, such symptoms have been related to dysfunctions in frontal cognitive processes such as attention, working memory and executive functions. This study uses standardized neuropsychological instruments to analyse the degree to which these processes are affected in PWS. Methods  The sample comprised 16 individuals with a genetically confirmed PWS diagnosis. Subjects’ IQ (Wechsler Adult Intelligence Scale), academic level, laterality and body mass index (BMI) were calculated. Attention, memory and executive functions were analysed using standard, widely employed neuropsychological tests. We compared the results of the sample group with the general population. Correlation analyses were carried out with IQ, academic level and BMI. Results  In all the neuropsychological measures focusing on attention, executive functions and visuoperceptual organization, the study sample scored significantly lower than the normative reference population. The scores of the tests used for measuring immediate memory were also significantly lower when trials required sequential processing, although not when they required simultaneous processing. In the memorization of a list of words, subjects showed an initial deficit which disappeared with repetition, enabling them to obtain scores similar to the reference population. No significant correlations were found with BMI, and a higher IQ or academic level did not improve scores in the majority of tests. Conclusions  The study shows a deficit in elementary frontal cognitive processes in PWS patients. This deficit may be involved in the social behaviour disorders that characterize such patients, as described in other development or frontal syndrome pathologies. However, we cannot affirm that the deficits found are specific to PWS; they could also occur in other causes of intellectual disability. Although in the study sample IQ did not correlate with frontal deficits, further research is needed to establish whether the neuropsychological alterations described form part of a cognitive phenotype for PWS. We