The Impact of Comorbidities on the Incidence of Cognitive Impairment and Dementia among Elderly Patients with Diabetes Mellitus

The rapid growth of older adult segment is striking not only in the United States but worldwide. One of the most serious and potentially high burdens on caregiver and economy are cognitive decline and Dementia. Diabetes and cognitive decline & dementia are strongly associated and prevalent among elderly. Better understanding of the mechanisms by which diabetes increase the risk of cognitive decline/dementia is crucial to improve management and prevention strategies in the future. In the light of mixed literature about the association of diabetes related diseases and factors, this dissertation will address that gap using a national representative sample, Health and retirement study, to examine (1) the impact of diabetes complications and co-existed diseases on the incidence of any-cognitive decline (Any-CI) / all-types dementia (All-D) among diabetic subjects compared to non-diabetic subjects, (2) the impact of hyperglycemia and diabetes complications and co-existed diseases on the incidence of Any-CI / All-D among diabetic subjects, while controlling for educational level, age, sex, ethnicity. Using Cox prpoprtional hazard modeling following subjects for 10 years, diabetes was associated with higher risk of both Any-CI and All-D. This association was independent of microvascular or macrovascular complications, other chronic diseases, or geriatric conditions. Stroke was the single largest risk factor for Any-CI / All-D in the general population and the diabetic cohort compared to other macrovascular diseases. Micorvascular diseases weren’t significantly associated with increased risk in both general and diabetic population. Hyperglycemia indicators (long duration, insulin use, and A1c ≥7%) were not associated with higher risk among diabetics. Other chronic diseases were not significantly associated with higher risk meanwhile geriatric conditions (like depressive symptoms, hearing loss and mobility) were associated with higher risk in general population only. There was a significant beneficial effect for lifestyle factors (physical activity, moderate drinking and no) on reducing the risk of developing both Any-CI / All-D in general population. Among diabetics, the negative impact of smoking was even higher. Further explorations of factors that may explain diabetes association with cognitive decline beyond clinical characteristics of the diseases are needed. The results suggest that Any-CI / All-D prevention strategies should focus on preventing diabetes in general population.