Type 2 Diabetes, Related Conditions, and Dementia

Abstract

The objective of this chapter is to provide a comprehensive review of the evidence linking type 2 diabetes and its related conditions, adiposity and hyperinsulinemia, with dementia. The mechanisms for these associations remain to be elucidated, but may include cerebrovascular and non-vascular mechanisms. Elevated adiposity in middle age is related to a higher risk of dementia. The evidence relating adiposity in old age to dementia is conflicting. Several studies have shown that hyperinsulinemia, a consequence of higher adiposity and insulin resistance is also related to a higher risk of dementia. Hyperinsulinemia is a risk factor for diabetes, and numerous studies have shown a relation of type 2 diabetes with higher dementia risk. In general, these associations are stronger for vascular dementia than for Alzheimer's disease. The implication of these associations is that a large proportion of the world population may be at increased risk of Alzheimer's disease given the trends for increasing prevalence of overweight, obesity, hyperinsulinemia, and diabetes. However, if proven causal, these associations also present a unique opportunity for prevention and treatment of dementia.