Impact of depression on quality of life in PKU children

Phenylketonuria (PKU) is a hereditary metabolic disorder. It is characterized by the accumulation of phenylalanine (Phe) metabolites in the brain and body. These metabolites can harm brain function, especially cognition, if they are not reduced by following a Phe-restricted diet early in life. Despite early treatment with a Phe-restricted diet, many neuro-psychiatric disorders are still reported in adults with PKU. The aim of this study is to assess depression in children with PKU. The study included 76 children aged 8-15 years. They were divided into late-diagnosed, early-diagnosed, and healthy control groups. Participants completed the Birelson depression scale and Peds QL 4.0 to measure health-related quality of life. Phe levels were measured at testing and averaged from the previous year. Children with PKU have higher depression scores than healthy controls. Late-diagnosed children have higher depression scores than early-diagnosed children (p = 0.001). Early-diagnosed children differ from controls only in reduced activity (p = 0.004). Late-diagnosed children show more loss of energy (85.7%), irritability (78.6%), and suicidal thoughts (21.4%). Quality of life is lower in children with PKU compared to controls, either regarding the total score or all domains. Quality of life is negatively correlated to Phe levels and depression scores (r =  - 0.32 and r =  - 0.51, respectively) while positively correlated to IQ levels (r = 0.74).Conclusion: Children with PKU show more depression and lower quality of life. These effects may be linked to diagnosis timing, long term Phe control, and IQ. Depression is more pronounced in late-diagnosed children than in early-diagnosed ones.