Blood Glucose Levels May Exacerbate Executive Function Deficits in Older Adults with Cognitive Impairment

Article type: Research Article

Authors: Pappas, Colleen^{a; *} | Small, Brent J.^b | Andel, Ross^{b; c} | Laczó, Jan^{c; d} | Parizkova, Martina^d | Ondrej, Lerch^d | Hort, Jakub^{c; d}

Affiliations: [a] Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, USA | [b] School of Aging Studies, University of South Florida, Tampa, FL, USA | [c] International Clinical Research Center, St. Anne’s University Hospital Brno, Brno, Czech Republic | [d] Department of Neurology, Memory Clinic, Charles University, 2nd Faculty of Medicine and Motol University Hospital, Prague, Czech Republic

Correspondence: [*] Correspondence to: Colleen Pappas, PhD, Department of Food Science and Human Nutrition, Iowa State University, 215 MacKay Hall, 2302 Osborn Drive, Ames, IA 50011, USA. Tel.: +1 515 294 3011; E-mail: capappas@iastate.edu.

Abstract: Background:Identifying protective factors that promote healthy cognitive aging is of importance due to the growing older adult population. Preventing chronic hyperglycemia may be one such way to preserve cognitive abilities, as high blood glucose levels have been associated with cognitive impairment and decline. Objective:To evaluate the influence of blood glucose levels on cognition among older adults using common neuropsychological tests and a spatial navigation task. Methods:The association between cognitive performance and blood glucose levels was assessed among 117 older adults classified as cognitively healthy, subjective cognitive decline, amnestic mild cognitive impairment, or Alzheimer’s disease dementia from the Czech Brain Aging Study. Cognitive abilities were measured by tests of verbal memory, nonverbal memory, working memory, visuospatial skills, and executive function. A test of spatial navigation known as the Hidden Goal Task was also used. Blood glucose levels were measured by glycosylated hemoglobin A1c (HbA1c). Analyses were performed using multiple linear regression controlling for age, gender, education, depressive symptoms, diabetes, and cognitive status. Results:A significant relationship was observed for HbA1c and executive function performance (beta = –2.46, SE = 0.92, p = 0.008). Following moderation analysis, this relationship was significant only among those with cognitive impairment (beta = –4.37, SE = 1.28, p = 0.001, 95% CI [–6.91, –1.83]). Associations between HbA1c and other cognitive domains were not significant (ps > 0.05). Conclusions:Higher HbA1c was associated with poorer executive function among persons with cognitive impairment, but not with performance on other cognitive domains. Maintaining proper glucoregulation may help preserve executive function performance among cognitively impaired older adults.

Keywords: Biomarkers, cognition, cognitive impairments, executive function

DOI: 10.3233/JAD-180693

Journal: Journal of Alzheimer's Disease, vol. 67, no. 1, pp. 81-89, 2019