Binge-Watching TV Linked To Brain Differences Associated With Dementia

If you’re a fan of a nightly binge-watch session on the sofa (hey, who isn’t?), it might be worth rethinking exactly how much time you spend passively gazing at the TV.

A recent study found people who watched TV ‘very often’ during midlife showed smaller volumes in brain regions linked to memory and areas of damage in the brain’s white matter that are associated with ageing, cognitive decline and even dementia.

Senior author David Raichlen, professor of biological sciences and anthropology at USC Dornsife, said: “For years we’ve focused on how much people sit. Our findings suggest we should also pay attention to what they’re doing while they’re sitting.”

The researchers suggested the results aren’t just because of people sitting still on the sofa for ages, as other types of sedentary activities (like sitting to work) did not have the same associations.

They looked at data from 1,700 adults, with an average age of 53, who had enrolled in the Atherosclerosis Risk in Communities (ARIC) Study between 1987 and 1989.

Participants were asked to report how often – on a scale ranging from “never” to “very often” – they watched TV during their leisure time. They were also asked how much of their workday they spent sitting.

After more than 20 years, participants had brain MRI scans. Compared with those who reported “never” or “seldom” watching TV, those who watched TV “very often” showed widespread structural differences across the brain.

In this group, the researchers found smaller volumes in brain areas that were associated with early signs of Alzheimer’s disease.

They also identified indicators of blood vessel disease associated with cognitive decline and dementia, as well as smaller occipital and frontal lobes, regions associated with vision and movement.

Differences persisted even when the researchers considered factors such as physical activity, diabetes, body mass index (BMI), smoking, and how much alcohol participants consumed.

The study found those who reported high amounts of sitting at work had larger frontal and occipital lobes, as well as reduced white matter hyperintensity volumes.

Researchers noted this indicated better brain health in work-sitters than among TV-sitters. This could be due to the intellectually stimulating nature of their sit-down jobs, they hypothesised.

Their not alone in their thoughts. Dr Soma Sengupta, a neurologist at Tufts Medical Centre, suggested that unlike reading, learning a new skill, or working, watching TV “often requires little active mental engagement”.

She told Prevention: “Over many years, less cognitive stimulation could contribute to less ‘exercise’ for brain networks involved in planning, memory and attention.”

When the MRI scans were separated by sex, researchers found that men were most impacted – most of the changes to the brain, both from TV watching and occupational sitting, were seen in this group.

The study authors suggested that, in future, MRIs should be taken at the start and end of the study so they can monitor changes over time.

They also suggested a different approach to health guidance around sedentary activities might be needed, focusing on reducing TV-watching.

Natan Feter, postdoctoral scholar in the Human and Evolutionary Biology program at USC Dornsife, added: “We frequently encourage the public not to spend too much time sitting down, but experts may want to expand that recommendation to encompass the activities done while sitting, since those seems to have distinct impacts on brain health.”

One study published in the American Academy of Neurology found that a decline in thinking skills and memory can be staved off by regularly reading and writing.

Drinking less, exercising more, eating a balanced diet, and avoiding smoking can benefit brain health and lower your risk of dementia, too.

In 2018, a 44-year-long study published in the journal Nature showed a link between cardiovascular fitness, as measured by a cycling test, and an 88% lower incidence of dementia among women.

Even walking regularly can benefit your brain. A 2022 paper found that just 3,800 steps a day may lower your likelihood of developing dementia by 25%, with increasing benefits up to 9,800 steps.