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Prader-Willi syndrome

Psychological and behavioural characteristics

Society for the Study of Behavioural Phenotypes logo

Prader-Willi syndrome is characterised by a number of distinctive psychological and behavioural features. Motor and language development are significantly delayed, and there are difficulties with gross motor skills, co-ordination and balance, voice problems (primarily hypernasality) and multiple articulation errors resulting in reduced intelligibility. These speech production problems are likely to be due at least partly to the early hypotonia and also the facial abnormalities associated with the syndrome. Spoken language is often considerably poorer than comprehension of language. Overall, cognitive abilities range from moderate learning difficulties through borderline abilities to average abilities or better, but usually with multiple learning disabilities. Severe learning difficulties are not commonly found.

The children tend to have an unusual cognitive profile, with particular strengths in visual organisation and perception, and in academic achievement tasks such as reading and vocabulary. Unusual skill with jigsaw puzzles is often noted. In contrast, auditory information processing and sequential processing are relatively weak, and most individuals have specific difficulties with arithmetic, writing, visual and auditory short-term memory and auditory attention.

Behaviourally, children with Prader-Willi syndrome tend to be floppy, sleepy and passive in the first year. Their muscle tone begins to improve towards the end of the first year and they become more active and alert. They are often described as easy-going, friendly and affectionate; but behavioural difficulties become increasingly apparent and severe with age. These are often related to the insatiable desire to obtain food, which develops between one and four years of age and is accompanied by excessive or rapid weight gain, and is physically, emotionally and socially debilitating. Excessive intake of food may cause life-threatening obesity and often involves foraging for food, stealing and hoarding food. Research shows that people with Prader-Willi syndrome think a lot more about food than other people, and may continue to eat at a steady rate as long as food is available.

Dietary management is the corner stone of managing the obesity. Typically, carers have to limit access to food and take over total control of food intake. Behaviour modification methods which rely on reinforcement and self-monitoring as part of weight control and exercise programmes, are also required. Long-term maintenance of weight loss is difficult to achieve, and problems with weight control can become worse in adult life when, with increased independence, food is more readily available.

Outbursts of rage and aggression, stubbornness and belligerence, are common in affected individuals, beginning around age three to five, becoming more marked later in childhood and persisting into adulthood. Tantrums and aggression may be related to wanting access to food, but typically extend also to situations unrelated to food (for example in response to changes in routine), and may occur with little provocation. Between the episodes of difficult behaviour, individuals with Prader-Willi syndrome are usually described as being good natured, placid and co-operative. They may be over friendly, with impulsive chatter, but most are also reported to be immature and socially isolated. Compulsive/obsessive behaviours and anxiety-based difficulties, excessive worry, and self-injury by deliberately picking or scratching the skin, are further common difficulties. The above behaviours are believed to result from the combination of the physical aspects of the syndrome, the relentless hunger, and the psychosocial pressures of being obese, sexually immature and cognitively limited. Physical inactivity and passivity are commonly reported, as are various sleep disorders, for example frequent waking in the night due to breathing difficulties (sleep apnoea) and excessive daytime sleepiness. In addition, psychiatric symptoms such as hallucinations, paranoia, agitation, anxiety and depression have been described in some adolescents and adults with the syndrome.

View What are the symptoms? What are the symptoms?  |  Inheritance patterns and prenatal diagnosis View Inheritance patterns and prenatal diagnosis

Medical text written November 1991 by Contact a Family. Approved November 1991 by Professor M Patton, Professor of Medical Genetics, St Georges Hospital Medical School, London, UK and Dr J E Wraith, Consultant Paediatrician, Royal Manchester Children's Hospital, Manchester, UK. Psychological and behavioural characteristics written November 1998 by Dr O Udwin, Consultant Clinical Child Psychologist, Society for the Study of Behavioural Phenotypes. Medical text last updated November 2004 and Psychological and behavioural characteristics last reviewed November 2004 by Dr J Whittington, Senior Research Associate, Section of Developmental Psychiatry, Department of Psychiatry, University of Cambridge, Cambridge, UK.

 

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