People who have risk factors for heart disease like diabetes, high blood pressure and obesity may also be more likely to develop structural changes in the brain that can lead to dementia, a recent study suggests.
Researchers examined data on 9,772 adults, ages 44 to 79, who all had at least one MRI brain scan and provided general health information and medical records for the analysis.
The researchers looked for associations between brain structure and so-called vascular risk factors. They found that except for high cholesterol, all of the other vascular risk factors – smoking, high blood pressure, high pulse pressure, diabetes, and obesity – were linked to abnormal brain changes seen in dementia.
And the more vascular risk factors a person had, the poorer was their brain health, as evidenced by greater brain shrinkage, less gray matter (tissue mainly on the surface of the brain) and less healthy white matter (tissue in deeper parts of the brain).
"There are some things that contribute to cognitive and brain aging that we cannot change (like our genes), so you could look at this like a list of things that we can have some agency over – so-called 'malleable' risk factors," said lead study author Professor Simon Cox of the University Of Edinburgh in the UK.
"There are so many other benefits to improving your cardiovascular health (improving diet, weight, exercise, blood sugar control) and stopping smoking, but in combination with other good evidence out there, maintaining brain health is probably another one," Prof Cox said by email.
The strongest links between the vascular risk factors and brain structure were in areas of the brain known to be responsible for our more complex thinking skills, and which deteriorate during the development of Alzheimer's disease and dementia.
Risk factors for heart disease appeared to impact brain health just as much in middle age as they did later in life, researchers report in the European Heart Journal.
And the risk of structural changes in the brain associated with cognitive decline also increased with each additional vascular risk factor, even in adults who appeared otherwise healthy, the study found.
Smoking, high blood pressure and diabetes were the three vascular risk factors that showed the most consistent associations across all types of brain tissue. High cholesterol levels were not associated with any differences in the MRI scans.
The study wasn't a controlled experiment designed to prove whether or how specific risk factors might directly cause dementia or cognitive decline.
"The precise mechanisms underlying these findings are not entirely clear," said Dr Jeffrey Burns, co-director of the University Of Kansas Alzheimer's Disease Center.
"The findings do underscore our increasing recognition that dementia is a complex syndrome and that vascular factors contribute to brain changes that we see and expect in people who are diagnosed with Alzheimer's disease," Dr Burns, who wasn't involved in the study, said by email.
Still, there's enough evidence of the connection for patients to do what they can to promote brain health as they age, said Dr Andrew Budson of the Veterans Affairs Boston Healthcare and Boston University School Of Medicine.
"Because smoking, hypertension, and diabetes were the strongest risk factors, if you have a number of risk factors, these are the most important ones to work on," Dr Budson, who wasn't involved in the study, said by email.
"Quit smoking cigarettes today," Dr Budson advised. "Control high blood pressure and diabetes through medications, aerobic exercise, and weight loss. These measures can reduce the daily brain damage that will otherwise occur."