TV, computer use linked to dementia — but not how you might expect

An analysis of more than 146,000 patients-worth of data has shown that some seated leisure activities are more dangerous than others when it comes to the development of dementia later in life.

The science is clear that a sedentary lifestyle may lead to early death, as too little physical activity is known to increase one’s risk of cardiovascular and metabolic diseases in particular.

David Raichlen, an anthropologist with the University of Southern California, wondered if the habit of sitting could have an impact on the mind, too.

In his new report, published Monday in the Proceedings of the National Academy of Sciences, the professor of human evolution answered that question, but with one caveat: Not all seated activities are equally risky.

“I do think people can consider tweaking their leisure activities to include less TV time and more cognitively engaged activities,” Raichlen told The Post.

USC researchers tapped into the UK Biobank database to compile a group of 146,651 people, all aged 60 years and older and who did not have dementia at the start of the survey. But at some point during the following 12 years, 3,507 of them would be diagnosed with the neurological disease.

After accounting for these participants’ other risk factors — such as obesity, alcohol consumption and employment type — Raichlen’s team revealed a correlation between time spent watching television and incidents of dementia.

On the other hand, those who spent less of their leisure time on the computer on average were also more likely to be diagnosed with dementia.

The results can’t firmly explain why sitting in front of one type of screen would be any different from sitting in front of another type — but when asked to hypothesize a reason, Raichlen told The Post he thinks the level of “cognitive engagement” required for computer-based activity — such as writing emails or playing games — may be key, whereas “TV watching is generally a cognitively passive activity.”

At the same time, the negative physiological impact of sitting too much — and, thus, falling out of shape — may go to encourage even more of their preferred sedentary activity.

Meanwhile, increased physical activity showed benefits among both high-risk groups. Previous study has also shown that some exercise and even light physical activity could help stave off cognitive decline.

More research must be done to find the cause behind these trends, especially as the number of people with dementia is expected to rise by 40% over the next 10 years, according to the World Health Organization.

The goal of Raichlen’s current line of research, then, is to uncover more links between physical activity — or inactivity — and brain health in order to help guide physicians on where and why to intervene on patients’ free time.