Watching Too Much TV May Actually Rot Your Brain After All, Study Finds
NEWS | 25 July 2026
If you click on the TV and hear a voice from your childhood saying, "That idiot box is going to rot your brain!" – you're not alone. My grandma said exactly that whenever she walked by me watching cartoons as a kid. Turns out, grammy wasn't entirely wrong. It's not just the sitting, which as we've now heard, isn't so great for longevity, or your brain, and may increase the risk of Alzheimer's and other types of dementia. When it comes to brain health specifically, a new study suggests that spending hours glued to the TV may have a negative effect that's not seen when the same amount of time is spent sitting at a desk solving problems, answering emails, or otherwise putting your gray matter to work. The research, published in Alzheimer's and Dementia: Journal of the Alzheimer's Association, followed more than 1,700 adults for nearly 24 years. It found that men (but not women) who frequently watched television in midlife had smaller brain volumes in regions vulnerable to Alzheimer's disease, along with more of the kind of damage to the brain that's associated with cognitive decline and dementia. Brain regions associated with the frequency of TV watching (left) and sitting during work (right). Red indicates areas associated with lower cortical volumes, while purple indicates volume increases. (Feter et al., Alzheimers Dement., 2026) In contrast, people whose jobs involved sitting for much of the day tended to have healthier-looking brains. Importantly, when the researchers accounted for differences in overall physical activity, that didn't seem to impact the outcome, so no, exercise didn't impact these findings. The striking sex difference surprised the researchers. "We found that the links between TV watching and brain structure were much stronger in men than in women," biological scientist Natan Feter from the University of Southern California told ScienceAlert. "This could be because men and women accumulate sedentary time differently – for example, women may interrupt their sitting more often – or because of biological differences in how the brain responds to prolonged sedentary behavior." Previous studies have found that women tend to prefer TV programming in shorter chunks, though they spend more time watching overall, while men's preferences for watching sports and movies are more likely to spend long, uninterrupted periods on the couch. Hormonal differences, lifestyle factors (such as childcare responsibilities), or differences in how male and female brains age could also play a role. The striking sex difference surprised the researchers. (pablo_rodriguez1/Canva) "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," says biologist David Raichlen from the University of Southern California. The data for the study came from 1,712 participants in the long-running Atherosclerosis Risk in Communities (ARIC) study. Volunteers, who were in their early 50s when they enrolled in the late 1980s, reported how often they watched television during their leisure time and how much they sat at work. About 24 years later, when they were in their mid-70s, their brains were scanned using an MRI. Researchers looked specifically at brain areas that are known to show early changes in Alzheimer's disease and related dementias, and areas of increased white matter hyperintensity (WMH) volume, which is "a marker of small vessel cerebrovascular disease associated with cognitive decline and dementia risk," according to the study. frameborder="0″ allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen> Compared to those who reported watching television "very often," people who reported sitting "always" during work had fewer white matter lesions and larger volumes in the frontal, parietal, and occipital cortex. Importantly, sitting itself wasn't consistently associated with poorer brain health – it depended on the context. Watching TV is considered a cognitively passive activity. On the other hand, even sedentary office work often involves planning, reading, writing, decision-making, and problem-solving. Previous research has suggested these kinds of mentally stimulating activities may help build "cognitive reserve", allowing the brain to better cope with age-related changes. The study has limitations. It used self-reported data from participants who estimated how much TV they watched or how much time they spent sitting at a desk, which is less reliable than objectively measured data. Research also can't prove that watching TV directly caused the brain differences, and clearly there's a gender element too. Other unmeasured lifestyle factors, such as snacking, drinking alcohol, or reclining or napping while "watching" TV, could have contributed to the findings. Still, the study tracked participants for nearly a quarter century, used MRI scans rather than cognitive tests alone, and results were consistent across analyses. Considering that there's research showing that book-readers live almost 2 years longer than non-readers, it does seem that there's some kind of difference between an active versus passive brain while sitting. Related: Not All Sitting Is Equal. One Type Was Just Linked to Better Brain Health. Things like puzzling, crafts, and even texting, which require your brain to work while you are sitting might also change how much sitting negatively impacts your brain, but "more research is needed to confirm," said Natan. So keep it in mind if you're settling in for another TV marathon tonight. Your brain might appreciate a few breaks – even if your streaming-service-of-choice doesn't provide commercial interruptions anymore. The research was published in Alzheimer's and Dementia: Journal of the Alzheimer's Association. This article was fact-checked by Rachel Garner and edited by Clare Watson. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
Author: Sciencealert Staff.
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