An adult phenylketonuria patient before and one year after reinstitution of dietary therapy

Background: In phenylketonuria (PKU) a phenylalanine restricted diet during the first years of life can prevent the development of severe cognitive da mage. Objective. Could neuropsychological or neurological changes occur in a 20-y ear-old patient with PKU (diagnosed early and treated until the age of 8 ye ars) after 12 years of normal nutrition and if so, can these changes be cou nteracted by reinstitution of a low phenylalanine diet? Methods: Psychological (intelligence, attention), neurophysiological (evoke d potentials) and neuroradiological examination (magnetic resonance tomogra phy [MRT] of the brain) were performed before and after one year of treatme nt with a diet low in phenylalanine. Results: During the reinstitution of dietary therapy we observed significan t improvements in attentiveness (percentage increase of 30), whereas intell igence subtests remained stable, a reduction in hyperreflexia, shortening o f the latencies of the evoked potentials and a decrease in periventricular pathological signal alterations as evaluated by MRT. Conclusions: The reintroduction of a diet low in phenylalanine improved psy chological and neurological symptoms in this PKU patient. We recommend a co nstant low-phenylalanine diet throughout life in patients with PKU.