Researchers identify genetic link underlying type 2 diabetes and Alzheimer's disease

Although epidemiological evidence has indicated that certain people with type 2 diabetes (T2D) are at higher risk to develop Alzheimer's disease (AD), no specific cause has yet been found to explain why or how these diseases are linked. But now new research suggests that AD and T2D share specific underlying genetic risk factors, according to a study conducted at the Icahn School of Medicine at Mount Sinai Hospital in New York.

To conduct this research, the investigators used genetic “databases”—large scale, genome-wide association study (GWAS) findings—to locate single nucleotide polymorphisms (SNPs) associated with T2D and AD. Then they tested these two groups of SNPs to find areas of overlap.

“We found 927 SNPs associated with both AD and T2D with p-value ≤0.01, an overlap significantly larger than random chance,” the authors wrote in a study published in Molecular Aspects of Medicine. “Among these, 395 of the shared GWAS SNPs have the same risk allele for AD and T2D, suggesting common pathogenic mechanisms underlying the development of both AD and T2D.”

They also found genetic anomalies in specific pathways, such as those related to immune responses, cell signaling, and neuronal plasticity. These are cellular processes in which abnormalities are known to contribute to both T2D and AD pathogenesis. Dysregulation of these pathogenic pathways could contribute to the elevated risks for AD among subjects with T2D, the researchers suggested.

“Our data highlights the need for further exploration of genetic susceptibility to Alzheimer’s disease in patients with T2D,” said the study’s lead author Giulio Maria Pasinetti, MD, PhD, Saunders Family chair and professor of Neurology at the Icahn School of Medicine and director of Biomedical Training in the Geriatric Research Education and Clinical Centers at J.J. Peters Bronx VA Medical Center in New York.