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A new study shows that dementia risk increased among older adults who spent more time exhibiting sedentary behaviors. Jo Bradford/Green Island Art Studios/Getty Images
  • A new study shows the more time older adults spend exhibiting sedentary behaviors, the greater their chance of developing all-cause dementia.
  • Inactivity is associated with poor cardiovascular health and unhealthy blood pressure levels, which is linked to a higher risk of dementia.
  • Physical activity reduces inflammation and insulin resistance, which may help reduce dementia risk.
  • To prevent dementia, experts recommend regular exercise at moderate-intensity levels.

Growing evidence demonstrates that sedentary behavior is linked with cardiovascular disease and mortality.

A recent study published in JAMA shows a link between sedentary behavior and incident dementia. The findings show the more time older adults exhibited sedentary behaviors, the greater their risk of developing all-cause dementia.

Lack of exercise may contribute to dementia risk for several reasons. First, physical activity is beneficial for cardiovascular health, and healthy blood pressure is linked to a lower risk of dementia. Exercise also lowers inflammation and improves insulin resistance, which helps decrease dementia risk.

To reduce your risk of developing dementia, moderate-intensity cardiovascular exercise is recommended.

For the present study, researchers gathered data from the UK Biobank, examining information from 49,841 adults ages 60 years or older who were not diagnosed with dementia when they wore an accelerometer.

Follow-up began when participants wore an accelerometer from February 2013 to December 2015, lasting until September 2021 in England, July 2021 in Scotland, and February 2018 in Wales.

Results from accelerometer readings show the more time older adults exhibited sedentary behaviors for an average of 10 hours per day, the higher the likelihood of all-cause dementia.

“We know that a sedentary lifestyle is associated with a number of poor health outcomes and chronic illnesses, including type 2 diabetes, high blood pressure, and heart disease,” Dr. Carolyn Fredericks, assistant professor of neurology at Yale School of Medicine, told Medical News Today.

“It is also associated with a significantly higher rate of dementia. This has been shown in prior studies but the current study is one of the very largest,” Dr. Fredericks said.

Matthew Stults-Kolehmainen, PhD, an exercise physiologist and researcher at Yale New Haven., told MNT: “Just as physical activity and exercise are associated with numerous, if not hundreds, of health benefits, the opposite is also true for ‘sedentarism.’”

“Excessive sitting and other sedentary behaviors are associated with obesity and being overweight, certain cancers, hypertension and metabolic disease, and even mental health problems, like depression and dementia. There is a place for the couch, and everyone deserves a break, but we should not be anchored to our furniture if we are concerned at all about physical and mental health.”

— Matthew Stults-Kolehmainen, PhD, exercise physiologist and researcher

Despite the findings from the new study, more rigorous research is needed to better understand the link between inactivity and dementia risk.

“We don’t understand the exact mechanisms, but exercise is also associated with changes in brain areas (such as the hippocampus) that are important for memory formation, such as increased gray matter in those regions,” Dr. Fredericks said.

Dr. Fredericks explained why exercise is important for overall health, including preventing dementia:

  • Exercise improves cardiovascular health, and we know that better cardiovascular health — healthy blood pressure and cholesterol, for example — are linked to a lower risk of dementia.
  • Exercise reduces the risk of insulin resistance and, down the line, diabetes, and diabetes is linked to higher dementia risk.
  • Exercise reduces overall inflammation in the body, which also helps reduce dementia risk.

Dr. Liron Sinvani, director of geriatric hospitalist services at Northwell Health, noted that there are shared risk factors between a sedentary lifestyle and dementia.

“The link between a sedentary lifestyle and dementia is thought to be primarily through shared risk factors including high blood pressure, heart disease, diabetes, and obesity,” Meaning that a sedentary lifestyle increases a person’s risk of these chronic conditions which are known to be risk factors for dementia.”

— Dr. Liron Sinvani, geriatric hospitalist

Stults-Kolehmainen noted that increased levels of brain-derived neurotrophic factor (BDNF) may also play a role.

“Physical activity is known to enhance BDNF, which is partially responsible for neurogenesis (formation of neurons),” Stults-Kolehmainen explained to MNT.

According to experts, moderate-intensity cardiovascular exercise could help prevent cognitive decline and lower dementia risk.

Dr. Fredericks described moderate-intensity cardiovascular exercise as engaging in physical activity at an intensity that allows you to talk with a friend without being completely out of breath.

“The research suggests about 30 minutes of moderate-intensity cardio daily is enough to significantly decrease the risk of memory loss as you get older,” Dr. Fredericks said.

Dr. Sinvani added: “Given that sitting can be thought of as the new smoking, it is critical to improve inactivity. The right time to start is today. Physical activity is important at any age.”

If you’re interested in getting more exercise but you’re not sure where to start, experts recommend trying activities you enjoy.

“Participating in enjoyable activities makes them easier to sustain. Group activities and classes can serve as physical activity as well as social interactions, which have also been shown to reduce the risk for dementia. For older adults, it is important to discuss your physical activity plan with your physician or primary care provider before starting to ensure safety, especially in those with existing high blood pressure or heart disease. It is also important to start gradually and increase activity as tolerated.”

— — Dr. Liron Sinvani, geriatric hospitalist

While it’s important not only to exercise more and be more active, it’s also crucial to sit less, Stults-Kolehmainen explained.

“Some people who exercise 30 minutes a day [or more] also get in 8 hours or more of sitting a day, which seems to counter-balance the positive effects of exercise,” Stults-Kolehmainen. “On the other hand, some people who get no exercise are on their feet all day, with little sedentary time.”

Stults-Kolehmainen concluded that it’s important to be “mindful of all movement and sedentary behaviors across all waking hours” and suggested short bursts of “exercise snacks” at regular intervals to help reduce overall sitting time.