Although people with
intellectual disabilities are at increased risk for
psychiatric disorders, the type and rate of these problems differ between those with different causes for their retardation. In this paper, we review behavioural and psychiatric problems in persons with
Prader-Willi syndrome, a disorder caused by a paternally derived deletion at chromosome 15(q11-q13) in about 70% of affected patients, and by maternal
uniparental disomy in the majority of the remaining patients. In addition to the syndrome's characteristic
hyperphagia and food seeking, individuals with
Prader-Willi syndrome also have increased risks of nonfood, compulsive behaviours. These include
skin picking, which is highly prevalent, as well as more variable rates of hoarding, redoing and concerns with symmetry, exactness, cleanliness, ordering and arranging. Relative to others with
mental retardation, persons with
Prader-Willi syndrome are at a marked increased risk for developing full-blown,
obsessive-compulsive disorder. In addition, many people with
Prader-Willi syndrome show increased rates of tantrums, oppositionality and aggression. Recent findings suggest that they also have an increased risk of
psychotic disorder or affective illness with a psychotic component, especially young adult patients and those with the maternal
uniparental disomy as opposed to paternal deletion. Dietary approaches include a reduced-calorie diet and increased physical activity, as well as close supervision around food and keeping food locked away. To date, neither
CNS stimulants nor
anorectic agents have been effective in treating
hyperphagia, in part because
hyperphagia in
Prader-Willi syndrome is attributed to decreased satiation as opposed to increased hunger. Treatment for compulsivity and maladaptive behaviours include: behavioural programming; a structured, predictable routine; extra help with transitions; family support; and
pharmacotherapy. Although formal
drug studies have yet to be conducted,
SSRIs have been effective in reducing
skin picking, compulsivity and aggressive episodes in some individuals with
Prader-Willi syndrome. Atypical
antipsychotics have also proven helpful in persons with psychotic features or extreme aggression and impulsivity. Largely on the basis of case studies, the risks and benefits of these and other drugs in
Prader-Willi syndrome are reviewed.
Drug trials that move beyond case studies and that assess the relative efficacy of behavioural treatments alone or in combination with
pharmacotherapy are sorely needed.