A new study adds to a growing body of evidence that people who have risk factors for heart disease in middle age are at increased risk of developing Alzheimer’s and other forms of dementia later in life. Some risk factors, like having diabetes, raise the risk almost as much as carrying a gene that raises Alzheimer’s risk late in life.

In addition to diabetes, smoking and high blood pressure in middle age also raised the risk for dementia, the current study showed. Both can lead to problems with the blood vessels, or vascular system, throughout the body, including the brain.

Earlier reports have shown that being overweight or leading a sedentary life, both factors for heart disease, likewise raise the risk of dementia.

“The health of your vascular system in midlife is really important to the health of your brain when you are older,” said Dr. Rebecca F. Gottesman, an associate professor of neurology and epidemiology at Johns Hopkins and the lead researcher of the study. Poor blood flow to the brain can lead to the onset of dementia, or make symptoms of Alzheimer’s worse, studies show.

The findings, presented at the American Stroke Association’s International Stroke Conference 2017 in Houston in February, come from an ongoing long-term study of more than 15,000 men and women that began in 1987. Those who had heart risks at the start of the study, when they were 45 to 64 years of age, were more likely to develop Alzheimer’s and other forms of dementia in old age.

During the study period, lasting about 25 years, more than 1,500 people developed dementia. The researchers calculated that those who had diabetes in middle age were 77 percent more likely to develop dementia in old age. “Diabetes raises the risk almost as much as the most important known genetic risk factor for Alzheimer’s disease,” carrying the APOE-E4 gene, Dr. Gottesman said.

Those who smoked at midlife were 41 percent more likely to develop dementia than those who didn’t smoke or who were former smokers. Having high blood pressure — or a reading of greater than 140/90 mm Hg — increased the risk by 39 percent; while having borderline hypertension (between 120/80 and 139/89) increased the risk by 31 percent compared to those with normal blood pressure.

Overall, the risk of dementia was highest in individuals who were older, carried the gene known to increase Alzheimer’s risk, or had high blood pressure, diabetes or were current smokers in midlife.

“If you knew you carried the gene increasing Alzheimer’s risk, you would know you were predisposed to dementia,” Dr. Gottesman said. “But people don’t necessarily think of heart disease risks in the same way. If you want to protect your brain as you get older, stop smoking, watch your weight, and go to the doctor so diabetes and high blood pressure can be detected and treated as early as possible.”

Leading a healthy lifestyle, including a heart-healthy diet and getting regular exercise, will also help to lower dementia risk, experts say.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.

Source: Rebecca F. Gottesman, MD, Ph.D., Marilyn Albert, Ph.D.; Alvaro Alonso, M.D., Ph.D, et al: International Stroke Conference (ISC) 2017. Abstract 98. Presented February 22, 2017.