Managing cholesterol might help reduce Alzheimer's risk, says researchers, including one of Indian-origin, who identified a genetic link between the progressive brain disorder and heart disease.

Examining DNA from more than 1.5 million people, the study showed that risk factors for heart disease such as elevated triglyceride and cholesterol levels (HDL, LDL, and total cholesterol) were genetically related to Alzheimer's risk.

However, genes that contribute to other cardiovascular risk factors, like body mass index and Type-2 diabetes, did not seem to contribute to genetic risk for Alzheimer's. "The genes that influenced lipid metabolism were the ones that also were related to Alzheimer's disease risk," said Celeste M. Karch, Assistant Professor at the Washington University's School of Medicine. 

Thus, if the right genes and proteins could be targeted, it may be possible to lower the risk for Alzheimer's disease in some people by managing their cholesterol and triglycerides, added Rahul S. Desikan, Assistant Professor at the UCSF.

For the study, published in the journal Acta Neuropathologica, the team identified points of DNA that increase the risk of cardiovascular disease and also heighten the risk for Alzheimer's disease. The team looked at differences in the DNA of people with factors that contribute to heart disease or Alzheimer's disease and identified 90 points across the genome that were associated with risk for both diseases. 

Their analysis confirmed that six of the 90 regions had very strong effects on Alzheimer's and heightened blood lipid levels, including several within genes that had not previously been linked to dementia risk. These included several points within the CELF1/MTCH2/SPI1 region on chromosome 11 that previously had been linked to the immune system.

The researchers confirmed their findings in a large genetic study of healthy adults by showing that these same risk factors were more common in people with a family history of Alzheimer's, even though they had not themselves developed dementia or other symptoms such as memory loss.

"These results imply that cardiovascular and Alzheimer's pathology co-occur because they are linked genetically. That is, if you carry this handful of gene variants, you may be at risk not only for heart disease but also for Alzheimer's," Desikan said.