By Emily Woodruff
Why do some people develop dementia, when others live well into old age without memory problems? While scientists are still figuring out the answer to that question, it’s becoming more apparent that there isn’t just one reason people get dementia—it’s a combination of factors. Researchers focused on four of those potential factors in a recent study that examined how each affects dementia risk: age; whether someone is married, divorced or widowed; weight; and amount of sleep.
The researchers chose those factors because most are modifiable, meaning a person has some control over them.
“By focusing on modifiable risk factors, we are hoping to identify disease risk factors that are amenable to change, enabling the possibility of preventing dementia,” explained corresponding author Rhoda Au, PhD, professor of anatomy and neurobiology.
Boston University School of Medicine scientists looked at data from 1979 to 1983 collected from a project called the Framingham Heart Study. They tracked who developed dementia over the next 30 years, and found that dementia showed a correlation with increasing age, as expected, but also with being a widow, a low Body Mass Index, and getting less than the recommended eight hours of sleep in mid-life.
Age is considered the single greatest risk factor for Alzheimer’s disease, which rarely affects people under the age of 65. In fact, one in three seniors in the U.S. die with some form of dementia.
Being underweight has been tied to dementia risk in the past—a 2015 study showed that people who had a BMI lower than 20 had a 34 percent higher risk of dementia. However, previous studies found that obesity increases risk of dementia, along with risk of heart disease and diabetes, both of which skyrocket a person’s chances of developing dementia.
And while being married has been shown to have benefits for the brain, other studies have pointed out that having close friends might be just as good when it comes to dementia prevention.
“The link with marital status is not well established and we need to see more research before we could confidently say that this contributes to our risk,” said James Pickett, Ph.D., Head of Research at Alzheimer’s Society.
Lack of sleep and abnormal circadian rhythms have long been associated with dementia, but some studies suggest that abnormal sleep in mid-life is an indicator that Alzheimer’s is already on its way. It then becomes a question of which came first: Did the poor sleep lead to Alzheimer’s, or did impending Alzheimer’s cause the disruption in sleep?
But experts not involved in the study said that the length of the study indicated that the risk factors examined probably were not just early symptoms of the disease. “One of the strengths of this research is the 30-year follow up of the participants which indicates these changes are most likely to be risk factors rather than the early stages of the condition,” said Pickett.
Considering that there is no effective treatment for dementia, identifying risk factors people can control could reduce dementia risk—especially because the risk factors this study examined are easy to quantify.
“We wanted to identify information that any physician or even non-physician has easy access to in determining potential increased future risk for dementia,” said Au. “Most dementia screening tools require specialized training or testing, but the front line for screening are primary care physicians or family members,” said Au.
This study was published in the Journal of Alzheimer’s Disease.