Computers vs. TV: Which is Less Likely to Promote Dementia?

Existing offices – up cycling desksIt is a response to a growing body of studies showing that a sedentary lifestyle creates many health risks. Regular physical activity appears to confer a degree of protection against various problems, both physical and mental, and several findings suggest that this does not have to be Olympic-level training. Just walking around the apartment a few times a day seems to help.

Now, a team of researchers has looked at the opposite question: Are all forms of inactivity equal? The answer is probably no. While the specifics depend on the health issues involved, there is likely to be some good news for people reading this, as this computer use appears to be somewhat protective against dementia.

Get off your chair

The physical risks associated with inactivity are generally associated with decreased cardiovascular health, either directly or via obesity. Even a small amount of physical activity appears to be able to reduce these effects, although increased exercise generally appears to be better (details vary depending on the study and the exact risks examined).

But exercise also appears to improve mental health. It can be an effective treatment for depression and other disorders, and appears to help stave off some of the unfortunate effects of aging. “Exercise and physical activity have shown promising results in reducing rates of cognitive decline, structural brain atrophy, and risk of dementia in older adults,” the authors wrote, citing work in other studies.

Oddly enough, some of the studies noted in the new study were that many used hours of TV watching as a proxy for the amount of time spent inactive. While that may have been true a few decades ago, we’ve significantly diversified our inactivity since then, as computers and mobile devices offer new ways to feel like you’re doing something without having to do anything.

Therefore, the researchers decided to look at this in more detail and address some related questions. Their study design separated computer use and television watching, and looked at how each affected the emergence of mental problems associated with aging. It also examined whether physical activity could influence the association between sedentary behavior and problems associated with aging.

To do this, the researchers made use of the UK’s Biobank, a large database that combines anonymized demographics with the health outcomes of hundreds of thousands of UK citizens. For this work, the team excluded people under the age of 60 and focused the work on about 75,000 people who filled in detailed information about their activity level and recreational activities.

Not good, but better

Before we get into the findings, a little reminder: Work focused on the effect of sedentary behavior on mental problems. Physical health issues have not been examined – it is possible that something that looks relatively good in this analysis will generally be negative once physical problems are taken into account.

That far, what did they see? With control for age and gender, time spent watching television was associated with an increased risk of dementia (A Hazard ratio than 1.3, which means they were 1.3 times more likely to develop dementia). Physical activity reduces the risk very slightly. In contrast, computer use reduced risk by a slightly larger percentage, bringing the risk ratio down to 0.8.

The same trend prevailed when researchers divided the group into thirds and compared high, medium, and low television viewing and computer use. Controlling for additional factors such as diet, alcohol intake, and obesity did not change the outcome either.

Although the effect of physical activity was slight, the researchers tested whether it could offset some of the problems associated with high TV viewing or low computer use. High levels of exercise seem to have a somewhat protective effect, but it is a minor one.

mental reserve

Overall, the results suggest that we need to decouple the way we think about the problems associated with inactive activity. In terms of physical health, any type of inactivity may be roughly equivalent. But in terms of mental issues, the way you spend your inactivity matters – some means of being a sofa potato involve passive consumption, others involve a greater degree of mental activity.

In this sense, the results fit neatly into the large body of research that indicates that staying mentally active can provide a degree of protection against dementia. Things like reading and playing vocabulary games generally appear to reduce the risk of dementia, and the benefits seem to accrue even if reading occurs when people are relatively young. So, there is a reason why you should not be surprised by this general result.

However, there are still quite a few reasons to be careful. Among other potential issues, the researchers note that activity levels were only checked at one point in the participants’ history and were self-reported, which tend to be less accurate. It is also important to realize that computer time will involve a wide range of activities, some more involved than others. So there is still some work to do here. But the next time someone is yelling at you for wasting time reading Ars, you can tell them you’re protecting your mental health.

PNAS2022. DOI: 10.1073/pnas.2206931119 (About DOIs).