Your brain is bound to shrink as you age — it’s unavoidable. But there are certain lifestyle factors that hasten the process, according to a new study by researchers at University of California, Davis.
The four factors that were associated with faster declines in brain volume were:
• High blood pressure
• Cigarette smoking
• Being overweight or obese
The study included 1,352 adults who had an average age of 54 and did not have dementia at the start of the study. All were participants of the Framingham Offspring Cohort Study (the children of the participants of the original Framingham Heart Study).
To start, researchers administered a battery of tests, including measures for obesity, high blood pressure, diabetes and high cholesterol. Starting seven years later, they measured the participants’ brain size using MRI scans and also gave participants cognitive tests to gauge executive function, planning and organizational skills.
The researchers found that all four risk factors were associated with faster declines in brain size: people with high blood pressure in midlife more quickly developed a condition called white matter change, in which areas of blood vessels in the brain are damaged, compared with those who had normal blood pressure.
People with diabetes had faster shrinkage in a brain region called the hippocampus, which is involved with memory. Smokers had more rapid overall brain shrinkage than nonsmokers, and also showed faster white matter changes.
On cognitive tests, these participants showed declines in executive function, or the ability to make decisions, plan, organize, and pay attention to and remember details. People who were overweight or obese in middle age, for example, were more likely to be among the top quartile of those with the fastest rates of decrease in brain volume and the most rapid declines in executive function.
“We can’t cure disease or cure aging, but the idea of a healthy body, healthy mind is very real,” said Dr. Charles DeCarli, director of U.C. Davis’ Alzheimer’s Disease Center and a lead author of the study, in a statement. “People should stop smoking, control their blood pressure, avoid diabetes and lose weight.”
The findings are in line with previous research showing that damage to the cardiovascular system is associated with cognitive decline and increased risk of dementia. Controllable lifestyle factors like smoking, high blood pressure, obesity and diabetes all increase the chances of cardiovascular-system damage. This is among the first studies, however, to link these risk factors with reductions in brain size.
Based on their findings, the authors think brain shrinkage and reduced cognitive function may be more widespread than we know: while only 5% of the study participants had diabetes, for example, nearly 50% of all Hispanics in the U.S. who are over the age of 65 have the disease.
The study was published Tuesday in Neurology, the medical journal of the American Academy of Neurology.
Want to know what else might shrink your brain? Check out this post on the Atlantic Wire.
Meredith Melnick is a reporter at TIME. Find her on Twitter at @MeredithCM. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.