Depression, anxiety, and stress in young adults with phenylketonuria: associations with biochemistry.

Objective: Increasing concurrent phenylalanine to "off-diet" levels in adults with phenylketonuria (PKU) has been shown to lead to mood disturbances. However, the impact of controlled phenylalanine exposure across the developmental life span and mood stability remains questionable. The aim of this study was to investigate correlations between lifetime and concurrent phenylalanine (Phe) and tyrosine (Tyr) with levels of depression, anxiety, and stress in young adults maintaining a continuously treated diet for PKU.

Method: Eight young adults (6 females, 2 males) aged 15 to 25 years (mean = 19.37, SD = 3.62) recruited through the Royal Children's Hospital Brisbane, with early and continuously treated PKU completed the Depression Anxiety Stress Scale, which was correlated with lifetime and concurrent measures of Phe, Tyr, and Phe-Tyr ratios.

Results: There was a strong significant correlation between lifetime Phe and levels of anxiety and stress (p < .01). Greater Phe-to-Tyr blood ratios were indicative of increased depression and anxiety levels (p < .01).

Conclusions: An interaction between biochemical regulation and depression, anxiety, and stress levels was present in young adults with continuously treated PKU who were actively attempting to maintain dietary control. Strong associations were present with lifetime levels, suggesting a developmental impact of PKU-related biochemical exposure and the emergence of mood disturbances.