Type 2 diabetes, cognitive function and dementia: vascular and metabolic determinants.

Type 2 diabetes is a common metabolic disease with a rising global prevalence. It is associated with slowly progressive end-organ damage in the eyes and kidneys, but also in the brain. The latter complication is often referred to as "diabetic encephalopathy" and is characterized by mild to moderate impairments in cognitive functioning. It is also associated with an increased risk of dementia. To date, its pathogenetic mechanisms are largely unclear. Cognitive impairments in patients with type 2 diabetes have been associated both with vascular risk factors, such as hypertension and dyslipidemia, and with diabetes-related factors, such as glycemic control, duration of the disease and treatment modality. Studies that address these associations generally focus on statistical (in)dependence of certain risk factors in the association between type 2 diabetes and cognitive decline rather than the causality of the association, which, from a mechanistic point of view, is more relevant. In this review we describe the association between type 2 diabetes and cognitive dysfunction and dementia. Furthermore, potential determinants of impaired cognition in type 2 diabetes are addressed both from the perspective of statistical associations and from a mechanistic point of view. (c) 2007 Prous Science.