Glycated Haemoglobin (HbA1c), Diabetes and Neuropsychological Performance in Community-Dwelling Older Adults

Abstract

Aims: Given that diabetes is associated with cognitive impairment and dementia in later life, we aimed to investigate the relationship between glycated haemoglobin (HbA1c), diabetes and domain-specific neuropsychological performance in older adults. Methods: Cross-sectional cohort study using data from the Trinity- Ulster-Department of Agriculture (TUDA) study. Participants underwent detailed cognitive and neuropsychological assessment using the Mini- Mental State Examination (MMSE), Frontal Assessment Battery (FAB) and Repeatable Assessment for Neuropsychological Status (RBANS). Linear regression was used to assess associations between HbA1c, diabetes status and neuropsychological performance, with adjustment for important clinical covariates. Results: Of 4938 older adults (74.1 ± 8.3 years; 66.9% female), 16.3% (n = 803) had diabetes (HbA1c ≥ 6.5%; 48 mmol/mol), with prediabetes (HbA1c ≥ 5.7%–6.4%; 39–47 mmol/mol) present in 28.3% (n = 1395). Increasing HbA1c concentration was associated with poorer overall performance on the FAB [β: −0.01 (−0.02, −0.00); p = 0.04 per % increase] and RBANS [β = −0.66 (−1.19, −0.13); p = 0.02 per % increase]. Increasing HbA1c was also associated with poorer performance on immediate memory, visuo-spatial, language and attention RBANS domains. Diabetes was associated poorer performance on neuropsychological tests of immediate memory, language, visual-spatial and attention. Conclusions: Both increasing HbA1c and the presence of diabetes were associated with poorer cognitive and domain-specific performance in older adults. HbA1c, and not just diabetes status per se, may represent an important target in the promotion of optimal brain health in older adults.