Preventing mental retardation associated with gross obesity in the Prader-Willi syndrome.

Twenty-seven patients with Prader-Willi syndrome have been described, ten of whom did not receive comprehensive management, nine who were diagnosed and treated after becoming obese, and eight who were diagnosed in infancy and responded to early preventative treatment. Intelligence scores declined in the first two groups, but the group receiving early treatment maintained a mean IQ score 20 points higher than the other two. Even though the underlying mechanism of this disorder remains undefined, a comprehensive early intervention program appears to improve prognosis.