title: Tackling frontal lobe-related functions in PKU through functional brain imaging: a Stroop task in adult patients.
abstract: BACKGROUND
  Profound mental retardation in phenylketonuria (PKU) can be prevented by a low phenylalanine (Phe) diet. However, even patients treated early have inconsistently shown deficits in several frontal lobe-related neuropsychological tasks such as the widely accepted Stroop task. The goal of this study was to investigate whether adult patients exhibit altered brain activation in Stroop-related locations in comparison to healthy controls and if an acute increase in blood Phe levels in patients has an effect on activation patterns.
  
  
  METHODS
  Seventeen male, early-treated patients with classic PKU (mean ± SD age: 31.0 ± 5.2 years) and 15 male healthy controls (32.1 ± 6.4 years) were compared using a color-word matching Stroop task in a functional magnetic resonance imaging (fMRI) study at 3T. Participants were scanned twice, and an oral Phe load (100 mg/kg body weight) was administered to patients prior to one of the fMRI sessions (placebo-controlled). Activity in brain regions that are known to be involved in Stroop tasks was assessed.
  
  
  RESULTS
  PKU patients exhibited poorer accuracy in incongruent trials. Reaction times were not significantly different. There were no consistent differences in BOLD activations in Stroop-associated brain regions. The oral Phe administration had no significant effect on brain activity.
  
  
  CONCLUSIONS
  Neither a generally slower task performance nor distinctively altered functioning of brain networks involved in a task representing a subset of dopamine-dependent executive functions could be proven. Decreased accuracy and inconsistent findings in posterior areas necessitate further study of frontal-lobe functioning in PKU patients in larger study samples.
authors.affiliation: Department of Clinical Radiology, University Hospital Muenster, Albert-Schweitzer-Str. 33, 48149 Muenster, Germany.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Sundermann
authors.forename: Bettina
authors.initials: B
authors.lastname: Pfleiderer
authors.forename: Harald E
authors.initials: HE
authors.lastname: Möller
authors.forename: Wolfram
authors.initials: W
authors.lastname: Schwindt
authors.forename: Josef
authors.initials: J
authors.lastname: Weglage
authors.forename: Jöran
authors.initials: J
authors.lastname: Lepsien
authors.forename: Reinhold
authors.initials: R
authors.lastname: Feldmann
mesh_terms: D000328:Adult; D001519:Behavior / Q000502:physiology; D001921:Brain / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005625:Frontal Lobe / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007361:Intelligence Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D010649:Phenylalanine / Q000097:blood; D010661:Phenylketonurias / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000523:psychology; D010919:Placebos; D011859:Radiography; D055815:Young Adult
chemical_list: D010919:Placebos; D010649:Phenylalanine