The mechanism in a single gene, the cause for both Alzheimer's disease and Type 2 diabetes, has been identified by scientists.
The data show that a gene for a protein called SorCS1, which can cause Type 2 diabetes, impacts the accumulation of amyloid-beta (Abeta) in the brain. Abeta plays a key role in the development of Alzheimer's disease.
Sam Gandy of the Mount Sinai led the study, together with first author Rachel Lane, PhD, a postdoctoral researcher in Gandy's Lab.
Lane and Gandy analysed both the brains of mice genetically engineered to be deficient in SorCS1 as well as cells engineered to express high levels of SorCS1.
They found an increased level of Abeta in SorCS1-deficient mice, and low levels of Abeta in the cells overexpressing SorCS1.
"We knew that Type 2 diabetes could increase the risk for Alzheimer's disease, but we were not sure how that risk was caused or whether that diabetes risk would impact Abeta levels in the brain.
"These results elucidate a common mechanism between diabetes and Alzheimer's and will bring us a step closer to identifying effective treatments for both diseases," said Gandy.
The researchers were also interested to find that the SorCS1-deficient mice had decreased levels of the protein Vps35, which was linked to Alzheimer's by Scott Small of the Columbia University.
They propose that depleted SorCS1 may cause Vps35 levels to also decrease, leading to further accumulation of Abeta in mice.
"Alzheimer's and Type 2 diabetes are reaching epidemic levels, afflicting millions. Their risk factors overlap and include high cholesterol, obesity, vascular disease, and inflammation.
Now that we have a better understanding of where the connection between these two diseases originates on a molecular level, the next step is to develop drugs that will help reduce their devastating impact," said Gandy.
The study was published in the Journal of Neuroscience.