Getting older doesn’t mean your brain function has to decline too. New research out of London finds that being physically active in your forties is positively tied to better brain function later in life.

Their findings reveal that middle-aged people who engaged in moderate-to-vigorous intensity workouts every day at middle-age excelled in brain performance. Meanwhile, those who were mostly inactive all day, sleeping or engaging only in light workouts seemed to have poorer cognitive performance. 

Prior studies report greater total physical activity and moderate-to-vigorous physical activity as most favorable for brain function. But these studies failed to take sleep time into account which is generally the largest component of the day. 

To fill this knowledge gap, the team gathered data from the 1970 British Cohort Study which included individuals born across England, Scotland, and Wales in 1970 and followed up from young age to their adulthood. They were followed right up until they clocked 46 years and were asked to fill out questionnaires on their lifestyle. They were then given activity trackers to wear continuously for seven days. 

Next, to study their cognition, participants underwent cognitive tests that assessed their verbal memory and executive function.

Overall, the team involved 4,481 participants with an average age of 47 years. Results from the activity tracker showed that participants averaged roughly 51 minutes doing moderate-to-vigorous physical activity and about 5 hours 42 minutes doing light physical activity. Additionally, these participants were found to spend over 9 hours 16 minutes on average doing little to no activity and slept roughly 8 hours 11 minutes. 

Following this further, the researchers found that those who had a sedentary lifestyle did have better cognitive scores. They explained that this may be attributed to the fact that participants spent their time doing cognitively demanding tasks such as reading or working.

The team also found the link was stronger for executive function—which assessed processing speed and accuracy—than it was for memory.

Participants who engaged in moderate-to-vigorous physical activity and had sedentary behaviors showed the best link with cognition. However, those who shifted from more vigorous activities and rather spent their day being inactive, engaging in gentle activity, or sleeping had a quick decrease in cognition. 

Similarly, they observed a boost in cognition of up to 1.31 percent upon replacing as little as 9 minutes of being sedentary with more high-intensity exercise. Showing a huge benefit associated with a much greater decrease in sedentary activities.

At the same time, substituting at least 7 minutes of gentle exercise or sacrificing 7 minutes of sleep for a high-intensity workout was tied to roughly a 1.27 percent and 1.2 percent boost in cognition, respectively. 

Notably, though, sedentary behaviors were found to benefit the brain, but only after replacing 37 minutes of gentle activities or 56 minutes of sleeping.

So when participants actively shifted away from moderate to vigorous physical activity, their cognition started to decline. More specifically, when participants started replacing 8, 6, and 7 minutes from the average of more vigorous activity with being inactive, engaging in a gentle activity, or sleeping, respectively, they experienced a 1 to 2 percent drop in their cognition. 

Based on occupation type, the team found that those working sedentary desk jobs may enjoy the full benefit upon reallocating part of their time to vigorous activities than those who worked manual jobs. 

The researchers explain that the activity trackers could only capture the time spent in bed and not necessarily sleep duration or quality, perhaps the reason for the association with sleep.

“MVPA is typically the smallest proportion of the day in real terms, and the most difficult intensity to acquire. Perhaps partly for this reason, loss of any MVPA time whatsoever appeared detrimental, even within this relatively active cohort,” they write in the paper.

Although it’s worth noting that this is just an observational study and, hence, cannot establish cause.

Regardless, the role physical activity plays in helping cognition is evident. Particularly due to the increasing prevalence of age-related cognitive decline. Being sedentary for too long, sleeping most of the day, or engaging in gentle activities can be largely harmful to cognition in later life.

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