A study led by researchers at Icahn School of Medicine at Mount Sinai recently revealed that patients with type 2 diabetes can have specific genetic risk factors that lead to a higher risk of developing Alzheimer’s disease. The study was published in the journal Molecular Aspects of Medicine and is entitled “Shared genetic etiology underlying Alzheimer’s disease and type 2 diabetes.”
Type 2 diabetes is the most common form of diabetes, affecting 90 to 95% of the individuals diagnosed with the disease. It is estimated that 312 million people in the world suffer from the disorder. Patients with type 2 diabetes do not make enough insulin or do not use it properly, leading to insulin resistance and eventually to higher blood sugar levels (hyperglycemia). Insulin is a hormone essential to control blood sugar levels and convert sugar, starches and other foods into energy.
One major long-term complication of type 2 diabetes is the increased risk of developing Alzheimer’s disease, the most common form of dementia in the elderly, a neurodegenerative disorder characterized by cognitive deficits and behavioral problems. Alzheimer’s disease is estimated to affect almost 45 million people worldwide. The mechanism underlying the link between diabetes and Alzheimer’s disease is, however, unknown.
It has been previously suggested that diabetes and Alzheimer’s disease share genetic risk factors. Based on this assumption, researchers have now investigated the presence of single nucleotide polymorphisms (SNPs; a genetic change in a single DNA base-pair) associated with the two disorders based on recent large-scale genome wide association study (GWAS) findings. GWAS allow the identification of variations in the genetic code across populations.
Researchers found 927 SNPs associated with both type 2 diabetes and Alzheimer’s disease, a considerable overlap that suggested a common pathogenic mechanism. In total, 395 of the shared GWAS SNPs were found to have the same risk allele for both disorders. These SNPs were found in genes related to immune responses, cell signaling and neuronal plasticity, all processes known to be affected in type 2 diabetes and Alzheimer’s patients.
“We identified multiple genetic differences in terms of SNPs that are associated with higher susceptibility to develop type 2 diabetes [T2D] as well as Alzheimer’s disease [AD],” said the study’s senior author Dr. Giulio Maria Pasinetti in a news release. “Many of these SNPs are traced to genes whose anomalies are known to contribute to T2D and AD, suggesting that certain diabetic patients with these genetic differences are at high risk for developing Alzheimer’s. Our data highlights the need for further exploration of genetic susceptibility to Alzheimer’s disease in patients with T2D.”
The research team concluded that their findings support the link between type 2 diabetes and Alzheimer’s disease. The authors believe that the results might be important for the development of novel therapeutic approaches for type 2 diabetes patients who have a genetic predisposition for Alzheimer’s disease, ultimately reducing the risk of developing the later one.