In this 25th installment of our series on dementia, we delve into an often-overlooked aspect of health that could be influencing our brain health more than we realize – our sedentary lifestyle. The modern era has seen a dramatic shift in our daily routines, with sedentary jobs witnessing an 83% increase since 1950 according to the American Heart Association. Johns Hopkins Medicine in Baltimore, Maryland, notes that physically active jobs now constitute less than 20% of the US workforce, a steep decline from around 50% in the 1960s. This shift, propelled first by mechanization and then by the digital era, has resulted in an increase in time spent on devices and, consequently, more time spent sitting.
This sedentary behavior is not just a concern for our physical fitness but may also have implications for our brain health. A recent study published in the journal Jama, involving nearly 50,000 adults aged 60 and over, revealed a startling correlation: more time spent in sedentary behaviors is linked to a higher risk of dementia. The study, which utilized wrist-worn tracking devices, found that individuals sitting for 10 hours or more daily significantly increased their risk of developing dementia. This risk persists despite intermittent physical activity, suggesting that total sedentary time is a critical factor.
The implications of a sedentary lifestyle extend beyond physical health concerns like weight gain and cardiovascular disease. But what makes physical activity so crucial for brain health? Neurology professor Andrew Budson from Boston University School of Medicine and a lecturer at Harvard Medical School, author of books on memory and brain health, offers several insights.
Firstly, Budson notes that physical movement improves cardiovascular fitness, thereby reducing the risk of strokes, which can impair cognitive functions and potentially lead to dementia. He shares a personal anecdote where a lack of movement was deemed a contributing factor to a stroke experienced by his mother, which possibly accelerated her dementia.
Secondly, aerobic exercise, even of moderate intensity, increases growth factors in the brain. These factors not only help in preserving existing brain cells but may also contribute to the growth of new ones.
Thirdly, movement engages various brain functions beyond mere physical coordination. Our brains work hard to track movement, location, and balance, creating new connections and sometimes new brain cells in the process.
Budson emphasizes that the risk of dementia escalates with increased sedentary time. Citing the Jama study, he illustrates how the risk for dementia rose by 8% for 10 hours of sedentary behavior, 63% for 12 hours, and a staggering 321% for 15 hours. He underscores the importance of mental stimulation through cognitive activities and social interactions, but warns that these do not offset the negative effects of prolonged sitting.
In his own life, Budson adopts a proactive approach to integrate movement into his daily routine. He engages in 45 to 75 minutes of vigorous exercise daily, including stationary biking, cross-country skiing, or running. His home office is equipped with a walking station, where he conducts most of his work activities while on the move, clocking up to 13 kilometers a day. He also takes opportunities to walk around the office, engage in walking meetings, and opts to pick up lunch rather than having it delivered.
When working in his clinic, Budson ensures a significant amount of walking, as evidenced by his phone tracker, moving from room to room and avoiding elevators unless necessary.
To encourage more physical activity, one could start by maintaining an honest log of daily sitting time. Instead of tricking fitness trackers with minimal wrist movements, it’s crucial to engage in whole-body activity. Breaking the habit of prolonged sitting can start with small but significant steps – getting up, moving around, and incorporating physical activity into our daily routines. This approach not only benefits our physical health but is also crucial for maintaining brain health and reducing the risk of dementia.
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