title: Impaired facilitation of self-control cognition by glucose in patients with schizophrenia: a randomized controlled study.
abstract: OBJECTIVE
  Studies in healthy individuals show that exerting self-control consumes cognitive resources, which reduces subsequent self-control performance. Restoring the availability of blood glucose eliminates this impairment. Patients with schizophrenia are found to have self-regulatory dysfunctions. This study aims to investigate whether patient's (a) glucose facilitation effects will be impaired, and (b) will have exaggerated depletion in a self-control task.
  
  
  METHODS
  40 patients with schizophrenia-spectrum disorders and 40 normal controls were recruited. A two drinks (glucose vs. placebo)×two depleting phases (self-control depleted vs. non-depleted) between-groups design was used. We examined the blood glucose levels before and after the selfcontrol depletion phase and the subsequent performances in two self-control tasks (handgrip and Stroop tests) after the drink condition.
  
  
  RESULTS
  The four groups (depleting×glucose, depleting×placebo, non-depleting×glucose and nondepleting×placebo) of both patients and normal controls were comparable on a number of characteristics. The change in blood glucose level in the depleting group was significantly different from those in the non-depleting group. Two×two between-subjects ANOVAs were carried out to test the performances in the handgrip and Stroop tasks. Significant interactions were found in healthy controls regarding both tasks. However, a significant interaction was only found in patients regarding the handgrip task but not the Stroop task.
  
  
  CONCLUSIONS
  This study demonstrated an abnormal glucose facilitation effect in patients during a cognitive self-control task but not during a physical self-control task. The findings also suggested for the first time that a self-control depletion effect is intact in patients with schizophrenia.
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong.
authors.forename: Chung-Ming
authors.initials: CM
authors.lastname: Leung
authors.affiliation: Department of Psychiatry, Massachusetts Mental Health Center, Division of Public Psychiatry, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, United States.
authors.forename: William S
authors.initials: WS
authors.lastname: Stone
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong.
authors.forename: Edwin Ho-Ming
authors.initials: EH
authors.lastname: Lee
authors.affiliation: Department of Psychiatry, Massachusetts Mental Health Center, Division of Public Psychiatry, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, United States; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, United States.
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Seidman
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong; State Key Laboratory of Brain and Cognitive Sciences, University of Hong Kong, Hong Kong. Electronic address: eyhchen@hku.hk.
authors.forename: Eric Yu-Hai
authors.initials: EY
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001786:Blood Glucose; D003072:Cognition Disorders / Q000097:blood* / Q000209:etiology*; D005215:Fasting; D005260:Female; D005947:Glucose / Q000008:administration & dosage*; D018737:Hand Strength; D006801:Humans; D007389:Internal-External Control; D008297:Male; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000150:complications*; D012649:Self Concept; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D005947:Glucose
keywords: Cognition; Impulse control; Nutrition-based intervention; Willpower