A new study finds people with sedentary lifestyles are more likely to develop dementia, especially if they remain sedentary for 10 hours a day or more—the latest in an avalanche of research showing the best way to combat the geriatric ailment is exercise.
The researchers from the University of Southern California and University of Arizona examined a set of data that followed 49,841 older adults in the U.K. who wore devices on their wrists that measured movement for 24 hours a day for one week.
Six years after wearing the devices, 414 of the adults had developed dementia, 250 of whom spent more than 9.27 waking hours a day sedentary and 154 spent more than 10.43 waking hours a day sedentary, the researchers found.
This means, the researchers concluded, that spending around 10 or more hours of the day sedentary is “significantly associated” with higher rates of dementia.
However, while the increase in dementia rates rapidly increases after 10 hours a day spent sedentary, the same is not true for lower levels, less than 10 hours, which saw no increased dementia risk, which suggests as long as one keeps their sedentary time under 10 hours, they won’t see increased dementia risk, according to the study.
Despite the common advice to break up long periods of inactivity—such as time spent at your desk at work or on the couch watching TV—by taking short breaks every 30 minutes or so to stand up and walk around, the researchers found there was no difference between being sedentary for 10 hours consecutively or 10 hours sporadically throughout the day. “This should provide some reassurance to those of us with office jobs that involve prolonged periods of sitting, as long we limit our total daily time spent sedentary,” said David Raichlen, an author of the study and a professor at the University of Southern California.
While the study did find people who spent long periods of their days sedentary were more likely to develop dementia, the authors acknowledged more research is required to determine definitively if that sedentary behavior is the cause of the increased risk. The study noted a number of confounding variables—or an undetected third variable that could explain the increases in both sedentary activity and rates of dementia—could have affected the results. Additionally, the participants’ activity levels were only measured for one week, and it’s possible that the participants were more or less active that week than usual. Finally, the researchers acknowledged the wrist monitors were unable to determine a participant’s posture, which would’ve given them a more precise idea of their activity level, and they recommended future studies use a thigh-mounted monitor to collect that data. Despite these limitations to the study though, the core of their findings aligns with a number of other recent studies.
This research is the latest in a number of studies that have found a link between how much someone exercises and their likelihood of developing dementia. A paper published in the journal Neuron last week found when humans exercise, the hormone irisin circulates through their body and reduces deposits of a protein fragment called amyloid beta in a patient’s brain cells that causes Alzheimer’s, the most common form of dementia. Furthermore, the Alzheimer’s Society found 11 studies that, when examined together, showed regular exercise can reduce a person’s risk of developing dementia by approximately 30% and for Alzheimer’s specifically, it reduces the risk by 45%. While most available evidence points to exercise being the leading way to reduce dementia risk, other things can also help. A July study by researchers from Australia, Chicago and Minneapolis found completing puzzles, doing card games, playing chess, taking adult education classes and other challenging cognitive activities reduced the risk of developing dementia after the age of 70 by as much as 11%.
Outside of prevention, there have also been new dementia developments in the pharmaceutical space. In July, a first-of-its-kind medication made by drugmakers Biogen and Eisai received approval from the Food and Drug Administration. Lecanemab aims to slow dementia by clearing plaque in the brain. However, some in the medical community have expressed concerns about the drug’s safety.
Sedentary Behavior and Incident Dementia Among Older Adults (Journal of the American Medical Association)
Scientists Finally Discover Why Exercise Cuts Alzheimer’s Risk, Study Says (Forbes)
Puzzles And Games Cut Dementia Risk—But Socializing With Friends And Family Barely Helps, Study Finds (Forbes)
FDA Grants Full Approval For Alzheimer’s Drug, Despite Concerns (Forbes)