A prefrontal dysfunction model of early-treated phenylketonuria.

A prefrontal dysfunction model of early-treated phenylketonuria (PKU) is discussed. The biochemical perturbations caused by this genetic disorder have been found to result in depleted dopamine, a neurochemical that is critical for prefrontal cortical function. Studies of the neuropsychological sequelae of early-treated PKU in children are reviewed, and it is suggested that findings indicating executive function (EF) impairments are consistent with the prefrontal dysfunction hypothesis. An alternative model of the neuropsychological effects, that of a lefthemisphere dysfunction, is also discussed. Although a substantial amount of research has explored the neuropsychological performance of children with early-treated PKU, the extent to which these EF deficits are maintained into adolescence and adulthood is unclear. The neuropsychological expression of early-treated PKU across development requires further investigation and should provide a window on the general nature of brain development and function.