Watching TV Increases Dementia Risk by 20% But Using Computers May Protect the Brain Against It

Researchers at the University of Southern California analyzed 12 years of data from more than 146,000 patients that led a sedentary lifestyle. Their findings showed that some sedentary behaviors are more dangerous than others regarding the risk of developing dementia later in life.

Previous studies showed that a sedentary lifestyle leads to early death and a higher risk of cardiovascular and metabolic diseases. Study lead author David Raichlen, an anthropologist at USC, wondered whether it would also affect brain health and conducted the study.

Not All Sedentary Behaviors are Equal

In a paper published in the Proceedings of the National Academy of Sciences (PNAS), Raichlen wrote that not all sedentary behaviors are equally risky. Sedentary behaviors are activities that do not increase energy expenditure above resting level, which include sleeping, sitting, lying down, watching TV, and other screen-based entertainment.

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

Researchers tapped into the UK Biobank database to compile data of people aged 60 years old and above who did not have dementia at the start of the survey. After 12 years since the beginning of the study, 3,507 out of 146,651 patients have been diagnosed with dementia.

The team revealed a correlation between time spent watching TV and incidents of dementia, wherein the activity increases the risk by 20%, MailOnline reported. However, those who spent less leisure time on the computer were also more likely to be diagnosed with neurological disease.

The findings do not explain how watching TV could be different from using the computer. Raichlen told the news outlet that the level of cognitive engagement required for computer-based activity could be the reason, whereas watching TV is a generally passive activity.

More research is needed to find the cause behind this, but Raichlen pointed out that the findings help clarify associations of sedentary behavior with brain health and suggests that future studies should not look at the time spent in such behaviors but maybe at the type of behavior.

He noted that reducing cognitive passive TV watching behavior and increasing computer use that promotes cognitive activity are promising targets for reducing dementia risk.

Activities With Low Risk in Developing Dementia

Medical News Today reported a separate study using UK Biobank data. Researchers found that activities linked to a lower risk of dementia include physical and mental activities.

The study, titled "Physical and Mental Activity, Disease Susceptibility, and Risk of Dementia," published in June 2022 in the journal Neurology, reveals that those engaged in frequent exercise, household chores, and daily visits by friends and family are 35%, 21%, and 15% have a lower risk of developing dementia, respectively.

Lastly, they found that physical and mental activity protected against dementia regardless of each participant's genetic predisposition or family history.

Check out more news and information on Dementia in Science Times.