Not only is obesity responsible for roughly 300,000 deaths per year in the U.S., but it’s also linked to Alzheimer’s disease and other related dementias (ADRD), a recent study published in the Journal of the American Medical Association claims.
Researchers from the study analyzed data from more than 378,000 participants and evaluated eight modifiable risk factors most prominently associated with ADRDs—including midlife obesity, physical inactivity, low education, midlife hypertension, depression, diabetes, current smoking and hearing loss.
They found that obesity in midlife – defined as a body mass index (BMI) greater than or equal to 30 between the ages of 40 and 64 – is now leading to more cases of dementia than any of the other modifiable risk factors surveyed in the study. In addition, about a third of dementia cases in America were associated with a combination of these factors, with midlife obesity, physical inactivity and low education being the most prominent.
“Ten years ago, the number one dementia risk factor was physical inactivity. Now, it is midlife obesity, and physical inactivity is number two,” said Deborah Barnes, PhD, MPH, corresponding author and Professor of Epidemiology and Psychiatry at the University of California San Francisco. “This is because midlife obesity has increased dramatically over the past decade, increasing from 13% to 36%.”
Barnes and her colleagues noted that these risk factors also seem to differ by sex, race and ethnicity. While the most important modifiable risk factor was midlife obesity for both men and women, the “excess caseload” due to all eight modifiable risk factors was relatively higher among men compared to women.
Why does this matter for caregivers and older adults?
Even though the study found midlife obesity is the top modifiable risk factor for ADRDs, Barnes said about one in three cases of Alzheimer’s and dementia may be preventable through healthy lifestyle behaviors.
She said people may be able to lower their risk of developing dementia through a healthy lifestyle such as maintaining a healthy weight, engaging in physical activity and graduating from high school.
These findings could perhaps help reinforce for both patients and providers the idea that engaging in healthy lifestyle behaviors such as maintaining a healthy weight or regularly exercising, said Roch A. Nianogo, MD, PhD, assistant professor of epidemiology at the UCLA Fielding School of Public Health. That could then help prevent other chronic diseases such as heart diseases, which “could also play a critical role in Alzheimer’s disease and other dementia prevention.”
Why is obesity linked to dementia?
Barnes said one explanation is that obesity increases the risk of other conditions, such as diabetes, hypertension and heart disease, which are all associated with increased dementia risk. In fact, type 1 diabetics are 93% more likely to develop dementia, and another study found hypertension and midlife high blood pressure increased a person’s risk of cognitive decline and dementia. Past studies have also found problems in the heart can also contribute to the development of dementia.
In addition, midlife obesity has more than doubled in the last decade—from 13% in 2010 to 36% in 2018.
“The change in midlife obesity prevalence appeared to be the largest compared to other factors evaluated in the study,” Nianogo said, “which potentially propelled midlife obesity to become the major contributor to dementia nearly a decade later.”
Another reason could be related to chronic inflammation, he said. It is believed that chronic conditions such as obesity and type 2 diabetes could lead to chronic systemic inflammation including neuroinflammation (inflammation in the brain), which in turn could accelerate changes typically seen in Alzheimer’s.
What can I do to prevent or combat obesity?
With nearly two out of three (69%) U.S. adults considered overweight – and roughly one out of three (36%) considered obese – the issue is widespread across the country. And finding time to work out or get some form of exercise in the day isn’t always easy—especially if you have a busy work and caregiving schedule.
For people who don’t know where to start, Emily Johnson, a Seasons expert and the founder and creative director of StrongerU Senior Fitness, recommends starting with walking. She said walking is one of the most accessible forms of exercise and one that provides a big return on investment for both physical and brain health.
“Start by checking in with your primary health care provider before starting a new exercise routine. Once you’ve received the green light, start by walking for just 10 minutes, three times per week,” Johnson said.
She added you can increase your walks by a few minutes per week until your walks are one hour in length—or walk for shorter durations but more frequently.
For people who are busy and struggle to find time to exercise, Johnson recommends building exercise and movement into your daily routine so it becomes a habit, choosing activities that are enjoyable such as a fitness class, line dancing and square dancing, or finding a friend or group to be active with.
“Caregivers and older adults who struggle to find time to exercise should swap out sedentary visits for walking visits,” she said. “Instead of going to visit your mom or dad sitting around chatting, go for a walk together. The walk will benefit you both, and exercise actually gives us more energy to feel more capable of tackling busy schedules and long to-do lists.”