Computers vs TV: Which is Less Likely to Contribute to Dementia?

Standing tables – and even bicycle tablesis in response to a growing body of research showing that a sedentary lifestyle poses many health risks. Regular physical activity appears to offer some protection against a variety of problems, both physical and mental, and many findings indicate that this is not necessarily Olympic-level training. A simple walk around the apartment several times a day helps.

Now a team of researchers is looking at the opposite question: Are all forms of inactivity the same? The answer is probably no. While the details depend on the health issue, there is probably some good news for people reading this in that computer use appears to protect against dementia to some extent.

Get up from the chair

The physical risks associated with inactivity are generally associated with cardiovascular deterioration, either directly or through obesity. Even a small amount of physical activity seems to be able to limit these effects, although increasing exercise in general seems to be even better (details vary by study and the exact risk being considered).

But exercise also seems to improve mental health. It can be an effective therapy for depression and other disorders and appears to help prevent some of the unfortunate effects of aging. “Exercise and physical activity show promise for reducing cognitive decline, structural brain atrophy, and dementia risk in older adults,” the authors write, citing work from other studies.

One of the quirks of some of the studies noted in the new one is that some of them used hours spent watching TV as a proxy for time spent in inactivity. While this may have been true a few decades ago, since then we’ve greatly diversified our idleness, thanks to computers and mobile devices that offer new ways to feel like you’re doing something without actually having to actually do it.

Therefore, the researchers decided to study it in more detail and address some related questions. Their study design separated computer use and television viewing and looked at how each affected the onset of mental health problems associated with aging. It also looked at whether physical activity could influence the association between a sedentary lifestyle and problems associated with aging.

To do this, the researchers used the UK Biobank, a large database that combines anonymous demographic data and health outcomes of hundreds of thousands of UK citizens. For this work, the team excluded people under the age of 60 and focused on about 75,000 people who filled out detailed information about their activity levels and leisure time.

Not good, but better

Before we get to the results, a little reminder: the work focused on the impact of a sedentary lifestyle on mental health issues. Physical health problems were not examined – it is possible that what looks relatively good in this analysis may become an overall negative if physical problems are taken into account.

What from the road, what did they see? When controlling for age and sex, time spent in front of the TV was associated with an increased risk of dementia (a hazard ratio 1.3, meaning they are 1.3 times more likely to be diagnosed with signs of dementia). Physical activity reduced the risks very slightly. In contrast, computer use significantly reduced the risk, lowering the hazard ratio to 0.8.

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

Although the effect of physical activity was small, the researchers tested whether it could offset some of the problems associated with high TV viewing or low computer use. A high level of exercise appears to have some protective effect, but it is small.

Mental reserve

Overall, the findings suggest that we need to delineate the way we think about the problems associated with sedentary activity. From a physical health perspective, either type of inactivity can be roughly equivalent. But when it comes to mental issues, how you spend your inactivity matters – some ways to be on the couch involve passive consumption, while others involve more mental activity.

In this sense, the results fit well with a large body of research showing that staying mentally active can provide some protection against dementia. Things like reading and playing vocabulary games seem to reduce the risk of dementia overall, and the benefits seem to increase even when reading occurs at a relatively young age. Therefore, there is reason not to be surprised by this general result.

However, there is still ample reason to be cautious. Among other potential problems, the researchers note that activity levels were only tested at one point in the participants’ histories and were self-reported, which tends to be less accurate. It is also important to recognize that time spent in front of a computer will involve a wide range of activities, some of which are much more active than others. So there is still work to be done here. But the next time someone yells at you for spending time reading Ars, you can tell them you’re protecting your mental health.

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