Timing is everything: Executive functions in children exposed to elevated levels of phenylalanine.

This study addresses how the timing of a known biological insult affects the developmental progression of executive functions. The sample consisted of children exposed to elevated levels of phenylalanine, either postnatally, as in phenylketonuria (PKU; n = 46), or prenatally, as in maternal PKU (n = 15). Nonhyperphenylalaninemic siblings of children with PKU (n = 18) served as controls. Results indicated that elevated levels of phenylalanine are toxic to the neurological systems that manage executive functions and cognitive tempo. This toxicity is dose dependent, with higher levels of phenylalanine being more detrimental. Executive function difficulties noted in PKU are consistent with attention deficit hyperactivity disorder (ADHD)-inattentive type, whereas maternal PKU offspring had executive function difficulties consistent with ADHD-combined type. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive Strengths and Weaknesses in Children and Adolescents Homozygous for the Galactosemia Q188R Mutation: A Descriptive Study.

Children and adolescents (n = 25) with galactosemia homozygous for the common Q188R mutation (substitution of glutamine codon 188 with arginine) were group matched for sex and age with healthy control participants (n = 20). Participants were administered an abbreviated neuropsychological battery by a doctoral-level psychologist. Results indicate that children and adolescents with galactosemia function generally within the low average IQ range, with a small standard deviation (indicating a relatively homogeneous IQ profile), and have many features suggestive of left-hemisphere dysfunction. Word retrieval difficulties are a primary component of the galactosemia profile. In addition, participants with galactosemia have less well-developed executive functions. Child and parental reports of behavioral symptoms differ; parents reported that their children had more internalizing symptoms than the children with galactosemia self-reported. Cognitive complications in galactosemia appear to emerge even in well-treated children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)