Efect of a controlled diet program on behavioral-emotional disorders in patients with phenylketonuria

Phenylketonuria is a disorder due to deficiency of the phenylalanine hydroxylase enzyme. Delay or untreatement would cause impacts on motor-cognitive and individual-social skills. This study aimed to investigate the effect of a controlled diet program on behavioral-emotional disorders in patients with phenylketonuria.

In a quasi-experimental study, 60 patients with phenylketonuria referred to Hazrate Masoumeh Hospital in Qom (the seventh largest city in Iran) were studied. The data were collected using parents' strengths and difficulties questionnaire (SDQ) to assess the status of behavioral-emotional disorders in patients by one of parents. Data were collected before and after - a three-months controlled diet- intervention.

The mean of phenylalanine in the patients was 12.81 ± 5.89 mg/dl before intervention and was decreased to 11.88 ± 6.8 mg/dl after intervention and this difference was statistically significant (p=0.018). The most significant effect of intervention was on increase of prosocial behaviors equal to 45%, reduction of conduct problems 38.3%, reduction of hyperactivity-attention deficit problems by 35%, decrease of emotional symptoms by 35% (p<0.001).  The mean score of the questionnaire and its sub-scales including emotional symptoms, conduct and hyperactivity problems decreased significantly after intervention (p<0.001), and prosocial behaviors showed a significant increase (p<0.001).

A three-months regular and controlled nutritional intervention showed a positive effect on behavioral-emotional disorders in patients with phenylketonuria. The diet intervention reduces patients' problems in sub-scales of emotional symptoms, behavioral, and hyperactivity problems and promote the prosocial behaviors.