title: Decreased response inhibition in middle-aged male patients with type 2 diabetes.
abstract: BACKGROUND
  This study was performed to examine whether patients with type 2 diabetes have cognitive deficits associated with the prefrontal cortex (PFC).
  
  
  METHODS
  Twenty-seven middle-aged patients with newly diagnosed type 2 diabetes and 27 healthy controls underwent physical measurements and neuropsychological tasks. Response inhibition, reward prediction, and executive function were assessed by the Go/NoGo task, the reversal and extinction tasks, and the Wisconsin Card Sorting Test (WCST). To examine the interactions of being overweight with diabetes on cognitive performance, performance data were analysed by two-way ANCOVA with diabetes and overweight as factors and age as a covariate.
  
  
  RESULTS
  Patients with type 2 diabetes showed significantly decreased response inhibition in the Go/NoGo task (discriminability index: P = 0.001). There was an interaction of being overweight with diabetes on reaction time in the Go trials of the Go/NoGo task (P = 0.009). Being overweight was related to retained responses to the presentiment of reward in the extinction task (P = 0.029). The four groups showed normal cognitive performance in the WCST.
  
  
  CONCLUSIONS
  Our results showed that middle-aged, newly diagnosed and medication-free patients with type 2 diabetes have a particular neuropsychological deficit in inhibitory control of impulsive response, which is an independent effect of diabetes apart from being overweight.
authors.affiliation: Faculty of Human Sciences, Waseda University, 2-579-15 Mikashima, Tokorozawa-shi, Saitama 359-1192, Japan.
authors.forename: Kaya T
authors.initials: KT
authors.lastname: Ishizawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kumano
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakura
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Iwamoto