Psychopathology of patients treated early for phenylketonuria: results of the German collaborative study of phenylketonuria

Abstract

At the age of 13 years, 60 adolescents, suffering from phenylalaninemia due to hydroxylase deficiency, and their mothers were simultaneously investigated with a standardized psychiatric interview in order to determine the adolescents' psychiatric status. Forty symptoms related to emotional disorders, antisocial and conduct disorders, hyperkinetic syndromes, and specific symptoms like psychophysiological pains, enuresis, encopresis, tics, stereotypies, and eating disorders were examined. Severity level was rated as undisturbed, mild, moderate, and severe disturbance. Comparison with a representative sample of 191 age mates revealed a double rate of moderate disturbances for the PKU sample. There was no association between severity level and sex as well as mean phenylalanine level during the first 13 years of the patients' lives. No PKU specific diagnosis could be determined. WISC-R-IQ below 90 was associated with a threefold risk of more severe disturbance and patients with more than three adverse familial circumstances had a 50% chance of getting a psychiatric diagnosis. It is concluded that the observed disturbances result from stress associated more with the chronic condition than with the increased phenylalanine level.