Genes and cardiovascular health both affect dementia risk

A new Boston University School of Public Health (BUSPH) and School of Medicine (BUSM) study finds that genes and cardiovascular health can both raise or lower risk of dementia.

Published in the journal Neurology, the study finds that dementia-associated common gene variants or the APOE ?4 genotype can more than double dementia risk, but that good cardiovascular health can halve dementia risk. These effects are additive, meaning genes and cardiovascular health can independently add to or subtract from a person's risk of developing dementia.

"Just because you have a high genetic risk of dementia doesn't mean that you can't lower your risk by adopting a healthier lifestyle," says study lead author Dr. Gina Peloso, assistant professor of biostatistics at BUSPH.

Peloso and colleagues used data from 1,211 participants in the offspring cohort of the BU-based Framingham Heart Study, the longest-running cardiovascular disease study in the U.S. (The study began in 1948, and the offspring cohort are the original participants' children and their spouses.) The analysis included genetic information, cardiovascular health data from 1991-1995, and data from the Framingham Heart Study's regular dementia screenings beginning in 1998-2001.

The researchers found that participants with a high genetic risk score based on several common gene variants were 2.6 times more likely to develop dementia than participants with a low genetic risk score. The researchers also looked separately at the dementia-associated APOE ?4 genotype, found in 10-15% of the general population, and found that participants with at least one APOE ?4 allele were 2.3 times more likely to develop dementia than participants without one.

Previous research has suggested that cardiovascular health affects a person's risk of dementia and Alzheimer's. For this study, the researchers scored participants on the American Heart Association's seven components of cardiovascular health: physical activity, cholesterol, healthy diet, blood pressure, weight, blood glucose, and smoking status. They found that participants with a favorable cardiovascular health score were 55% less likely to develop dementia than participants with an unfavorable score.

The researchers did not find any interaction between genetic risk score or APOE ?4 and cardiovascular health, indicating that these risk factors independently affect dementia risk.

"We have long maintained that genetics is not destiny, that the impact of your family history and genetic risk can be lowered by healthy lifestyle choices. This is true for persons with low genetic risk and also for persons with high genetic risk of dementia, so it is never too soon and never too late to adopt a 'heart-healthy lifestyle," says study senior author Dr. Sudha Seshadri, founding director of the Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases at The University of Texas Health Science Center at San Antonio. She is also a professor of neurology at BUSM and the Framingham Heart Study's principal investigator in neurology.