Sitting for 10 Hours Daily Might Increase Dementia Risk by 63%

A recent study published in JAMA has highlighted a concerning connection between extended periods of sitting and an increased risk of developing dementia. This revelation has far-reaching implications for our health, as it suggests that even regular exercise may not be enough to counteract the detrimental effects of prolonged sitting. 

The study involved a substantial sample of 49,841 individuals aged 60 or older and aimed to provide objective measures of sitting time, moving beyond self-reported data. Researchers accessed data from the UK Biobank, a repository containing comprehensive information about the lives, health, and mortality of hundreds of thousands of British men and women. 

To obtain precise measurements of sitting and movement, many participants wore sophisticated activity trackers for a week after joining the study. These trackers minutely recorded their activities and periods of inactivity throughout the day. The researchers then tracked the medical status of these individuals for approximately seven years, specifically looking for hospital or death records related to dementia. 

The results of the study were eye-opening. Individuals who spent at least 10 hours per day sitting had an 8 percent higher risk of developing dementia within the next seven years compared to those who sat for fewer than 10 hours. The risk continued to escalate, reaching a staggering 63 percent higher risk for individuals who spent at least 12 hours a day sitting. 

David Raichlen, a professor at the University of Southern California who led the study, emphasized the cumulative impact of sedentary behavior. He pointed out that the hours spent sitting at the office, in front of the TV, in the car, and during other daily activities add up, significantly elevating the risk of cognitive and memory decline. 

One surprising finding from the study was that exercise alone did not appear to mitigate the risk associated with prolonged sitting. Even those who engaged in regular physical activity were just as prone to dementia if they spent long hours sitting. This implies that exercise, while crucial for overall health, may not be sufficient to counteract the harmful effects of excessive sitting. 

The study also examined the potential benefits of short breaks, such as standing up or taking brief walks during long periods of sitting. However, the data showed limited improvements among individuals who incorporated these breaks into their sedentary routine. The crucial factor appeared to be the total number of hours spent sitting each day. 

Although the study shed light on the risks associated with sitting, there are still questions about the potential benefits of standing or using standing desks as an alternative to sitting. The distinction between sitting and standing still in data from activity trackers can be challenging, making it unclear whether standing can effectively mitigate the risks associated with sitting. 

To reduce the risk of dementia, Raichlen suggested finding ways to sit less overall. For individuals whose jobs require extensive desk and computer time, he recommended seeking opportunities for movement during the day. This could include walking around the office while on the phone, scheduling walking meetings, or opting to pick up lunch instead of having it delivered. 

While this study offers compelling evidence of a link between prolonged sitting and an increased risk of dementia, it is essential to recognize that the study’s findings are associational and cannot definitively establish causation. Nonetheless, the message is clear: reducing sedentary behavior and increasing physical activity are vital steps in promoting both physical and cognitive health. As Raichlen succinctly put it, “Sit less, move more. That’s the message, and we probably can’t repeat it enough. 

Journal Reference  

Raichlen DA, Aslan DH, Sayre MK, et al. Sedentary Behavior and Incident Dementia Among Older Adults. JAMA. 2023;330(10):934–940. doi:10.1001/jama.2023.15231