BACKGROUND: Phenylketonuria (PKU) is an inborn error of metabolism caused by mutations in the phenylalanine hydroxylase (PAH) gene. When untreated, PKU leads to a significant intellectual deficiency. Although early initiation of dietary therapy allows normal cognitive development, low adherence to treatment may result in neuropsychological deficits, including attention problems. This study was performed to evaluate emotional and behavioral problems in early-treated children and adolescents with PKU using the Child Behavior Checklist – CBCL/6–18 answered by parents.

MATERIAL AND METHODS: The study included 36 PKU patients. The mean scores of internalizing, externalizing, and total problems, syndrome scales, and DSM-IV-oriented scales of patients were compared with those of controls. An analysis to evaluate the importance of adherence to treatment and presence of intellectual disability was also performed.

RESULTS: There were no significant differences between patients and controls for almost all CBCL/6–18 scales, with the exception of the Attention Problem Scale – CBCL-APS. The mean (±SD) of the CBCL-APS scores of patients (7.86±5.33) was considerably higher than the mean of the controls (6.07±4.37; p=0.016), but not different from the mean of a matched control subsample (6.69±4.46; p=0.316). The difference between the mean of the scores of DSM-IV/ADHD scale of patients (6.72±4.07) and controls (5.73±3.56; p=0.102) was not significant. Non-adherence to treatment and intellectual disability had a negative impact on both CBCL-APS and DSM-IV/ADHD scale scores.

CONCLUSIONS: Our findings indicate a significant prevalence of parents’ complaints of attention problems and hyperactivity in non-adherent to treatment and intellectually low performing patients with PKU.

Keywords: Attention, Child Behavior, Cognition, Patient Compliance, Phenylketonurias