title: Fasting glucose and glucose tolerance as potential predictors of neurocognitive function among nondiabetic older adults.
abstract: BACKGROUND
  Significant evidence has demonstrated that Type 2 diabetes mellitus and related precursors are associated with diminished neurocognitive function and risk of dementia among older adults. However, very little research has examined relations of glucose regulation to neurocognitive function among older adults free of these conditions. The primary aim of this investigation was to examine associations among fasting glucose, glucose tolerance, and neurocognitive function among nondiabetic older adults. The secondary aim was to examine age, gender, and education as potential effect modifiers.
  
  
  METHODS
  The study employed a cross-sectional, correlational study design. Participants were 172 older adults with a mean age of 64.43 years (SD = 13.09). The sample was 58% male and 87% White. Participants completed an oral glucose tolerance test as part of a larger study. Trained psychometricians administered neuropsychological tests that assessed performance in the domains of response inhibition, nonverbal memory, verbal memory, attention and working memory, visuoconstructional abilities, visuospatial abilities, psychomotor speed and executive function, and motor speed and manual dexterity. Linear multiple regressions were run to test study aims.
  
  
  RESULTS
  No significant main effects of fasting glucose and 2-hour glucose emerged for performance on any neurocognitive test; however, significant interactions were present. Higher fasting glucose was associated with poorer short-term verbal memory performance among men, but unexpectedly better response inhibition and long-term verbal memory performance for participants over age 70. Higher 2-hour glucose values were associated with reduced divided attention performance among participants with less than a high school education.
  
  
  CONCLUSIONS
  Mixed findings suggest that glucose levels may be both beneficial and deleterious to neurocognition among nondiabetic older adults. Additional studies with healthy older adults are needed to confirm this unexpected pattern of associations; however, findings have implications for the importance of maintaining healthy glucose levels in older adulthood.
authors.affiliation: a School of Nursing, University of Delaware , Newark , DE , USA.
authors.forename: Regina
authors.initials: R
authors.lastname: Sims Wright
authors.forename: Shellie-Anne T
authors.initials: SA
authors.lastname: Levy
authors.forename: Leslie I
authors.initials: LI
authors.lastname: Katzel
authors.forename: William F
authors.initials: WF
authors.lastname: Rosenberger
authors.forename: Zorayr
authors.initials: Z
authors.lastname: Manukyan
authors.forename: Keith E
authors.initials: KE
authors.lastname: Whitfield
authors.forename: Shari R
authors.initials: SR
authors.lastname: Waldstein
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism*; D003071:Cognition / Q000502:physiology*; D003430:Cross-Sectional Studies; D005215:Fasting / Q000097:blood*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests
chemical_list: D001786:Blood Glucose
keywords: Impaired fasting glucose; Impaired glucose tolerance; Neurocognitive function; Older adults; Type 2 diabetes