Diabetes, Cognitive Decline, and Genome-Wide Associations

Worldwide incidence rates of type 2 diabetes and Alzheimer's disease (AD) are consistently rising, mainly explained by a rise in the aging population. Over the last decade, numerous studies have identified a strong correlation between type 2 diabetes and cognitive decline, including mild cognitive impairment (MCI) (a clinical period that usually precedes AD) and AD. Intriguingly, the connection has been mostly attributable to insulin resistance and alterations in the insulin signaling pathway. Deficits in peripheral insulin functioning have been shown to alter cerebral insulin, leading to end-products of glucose toxicity along with increased β-amyloid deposition and neurofibrillary tangles, hallmarks of AD. To date, genome-wide association studies (GWAS) have begun to unravel specific genetic variants associated with MCI, AD, and type 2 diabetes. Separate GWAS scans have identified the same genetic variants in both AD and type 2 diabetes, thus underlining an important basis for future drug development research.