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People who frequently watch television in midlife may be more likely to develop brain changes associated with memory problems, cognitive decline and dementia later in life, according to new research.
The study, published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, suggests that what people do while sitting may matter just as much as how long they spend sitting.
Researchers analyzed data from approximately 1,700 adults enrolled in the Atherosclerosis Risk in Communities (ARIC) Study, a long-running U.S. project investigating cardiovascular and brain health. Participants, who were about 53 years old on average when they entered the study between 1987 and 1989, reported how often they watched television during their leisure time, ranging from “never/seldom” to “very often.” They also reported how much of their workday they spent sitting.
More than 20 years later, participants underwent brain MRI scans. Compared with people who rarely watched television, those who reported watching TV very often showed several structural differences in the brain.
These included smaller volumes in brain regions associated with memory and areas known to be vulnerable to Alzheimer’s disease. Frequent TV viewers also had larger volumes of white matter hyperintensities—areas of damage in the brain’s white matter linked to aging, stroke risk, cognitive decline and dementia.
Participants who watched television very often also had smaller frontal and occipital lobes. The frontal lobe plays a key role in executive functions such as planning, decision-making and problem-solving, while the occipital lobe is primarily involved in visual processing.
Importantly, the associations remained even after researchers accounted for a range of health and lifestyle factors, including physical activity, diabetes, body mass index, smoking and alcohol use.
One of the study’s most notable findings was that the observed differences were not simply tied to being sedentary.
While television viewing was associated with markers of poorer brain health, other forms of sitting showed a very different pattern. Participants who reported spending long periods sitting at work tended to have larger frontal and occipital lobes and lower volumes of white matter hyperintensities.
David Raichlen, professor of biological sciences and anthropology at the USC Dornsife College of Letters, Arts and Sciences, and Natan Feter, postdoctoral scholar in the Human and Evolutionary Biology program at USC Dornsife and corresponding author of the study, told Newsweek that the findings reinforce the idea that “not all sitting is equal for brain health.”
“Most of our waking hours are spent sitting, but our findings suggest that how we spend that time matters,” they said.
According to the researchers, television viewing is generally a cognitively passive activity, while many jobs that involve prolonged sitting may also require mental engagement. Sitting at work often involves problem-solving, decision-making and other higher-order cognitive functions that may help explain the contrasting brain health findings.
Raichlen and Feter said they were surprised by how different the patterns were between television viewing and occupational sitting.
“These findings reinforce the idea that the context in which people spend their sedentary time matters and highlight the need for future research to understand the biological and behavioral mechanisms underlying these differences,” they said.
The researchers believe there are several possible reasons television viewing may be linked to poorer brain health than other seated activities.
Unlike working, reading or using a computer, watching TV typically requires less sustained attention, problem-solving and mental engagement. It is also more likely to involve long, uninterrupted periods of sitting and may be accompanied by other unhealthy behaviors, such as snacking.
While the findings point to a connection between television viewing and brain structure, the researchers cautioned that the study cannot determine cause and effect.
The study also revealed notable differences between men and women. When researchers analyzed MRI results separately by sex, most of the associations between both TV viewing and occupational sitting were observed in men.
The findings add to growing evidence that different sedentary behaviors may have distinct relationships with long-term brain health, but the authors stress that more research is needed.
The study has several limitations. Television viewing habits were self-reported, which may be less accurate than directly tracking viewing time. Researchers also did not have brain MRI scans from the beginning of the study.
Future research that includes baseline brain scans could provide a clearer picture of how television viewing and other sedentary activities influence brain structure across the lifespan.
For now, the researchers say the findings support existing advice to limit prolonged sedentary behavior and suggest people may benefit from choosing more mentally stimulating activities when sitting.
“Our findings reinforce existing public health recommendations to reduce prolonged sedentary time,” Feter said. “They also suggest that, when possible, replacing passive sedentary behaviors such as prolonged TV viewing with more cognitively engaging activities, such as reading or learning a new skill, may be beneficial for brain health.”
Reference
Feter, N., Nanda, A., Hourihan, S., et al., Associations of distinct sedentary behaviors with cortical, subcortical, and white matter hyperintensity volumes: Evidence from the ARIC study, Alzheimer’s and Dementia: Journal of the Alzheimer’s Association, 2026, https://doi.org/10.1002/alz.71582
Contact Newsweek editors on this story: Kara Dolman and Emma Lee-Sang
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