The Turkish Journal of Pediatrics 2018 , Vol 60 , Num 6
Cognitive and behavioral impairment in mild hyperphenylalaninemia
S. Gülin Evinç 1 ,Emine Pektaş 2 ,Dilşad Foto-Özdemir 1 ,Yılmaz Yıldız 2 ,Yamaç Karaboncuk 3 ,Berrak Bilginer-Gürbüz 2 ,Ali Dursun 2 ,Ayşegül Tokatlı 2 ,Turgay Coskun 2 ,Ferhunde Öktem 3 ,H. Serap Sivri 2
1 Departments of Child and Adolescent Psychiatry Hacettepe University Faculty of Medicine, Ankara, Turkey
2 Departments of Pediatric Metabolism, Hacettepe University Faculty of Medicine, Ankara, Turkey
3 Ferhunde Oktem Ruh Saglığı Merkezi, Ankara, Turkey
DOI : 10.24953/turkjped.2018.06.001 Evinç SG, Pektaş E, Foto-Özdemir D, Yıldız Y, Karaboncuk Y, Bilginer-Gürbüz B, Dursun A, Tokatlı A, Coskun T, Öktem F, Sivri HS. Cognitive and behavioral impairment in mild hyperphenylalaninemia. Turk J Pediatr 2018; 60: 617-624. As elevated phenylalanine (Phe) is detrimental to brain functions, determining a safe upper limit of blood Phe is important for initiation of treatment plans and setting Phe targets in hyperphenlalaninemic patients. It is accepted that Phe levels below 360 μmol/L does not impair brain function and hence does not require treatment. Therefore, we aimed to compare cognitive functions and attention-related problems among healthy children and untreated patients with hyperphenylalaninemia (HPA). This study included 41 hyperphenylalaninemic patients (`all HPA group`) aged 6-16 years with untreated blood Phe between 240 and 600 μmol/L and 29 healthy controls. `All HPA group` was further divided into 2 subgroups according to their lifetime median blood Phe levels as `Phe 360-600 μmol/L` and `Phe 240-360 μmol/L` groups. Wechsler Intelligence Scale for Children–IV (WISC-IV), Conners` Continuous Performance Test (CPT), Strength and Difficulties Questionnaire (SDQ) and Schedule for Affective Disorders and Schizophrenia for School-Age Children: Present and Lifetime Version (K-SADS-PL) were performed as a comprehensive neurocognitive, attention and behavioral assessment. The study illustrated that `all HPA` patients had significantly lower scores on all WISC-IV indexes compared to controls, except for Working Memory. Both `Phe 360-600 μmol/L` and `Phe 240-360 μmol/L` subgroups had lower Full Scale intelligence quotient (IQ) and Verbal Comprehension scores compared to controls. `All HPA` patients also had longer reaction times and more peer problems than controls, indicating attention deficits and behavioral problems. Since the results demonstrated that children with untreated Phe levels between 240-360 μmol/L are at higher risk for cognitive and attention-related problems, lowering the `safe` upper Phe level should be considered. Keywords : hyperphenylalaninemia, cognitive functions, intelligence quotient
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