A recent study suggests that spending long hours watching television may be associated with structural changes in the brain, particularly among men, potentially increasing the risk of cognitive decline and dementia later in life.
The study analysed data from 1,712 participants with an average age of 53 at enrolment. Researchers followed the participants for nearly 24 years as part of the Atherosclerosis Risk in Communities (ARIC) study.
Participants were asked to report how frequently they watched television during their leisure time, as well as the amount of time they spent sitting at work. Approximately two decades later, they underwent MRI brain scans to assess changes in brain structure and overall brain health.
The findings showed that participants who reported watching large amounts of television had smaller volumes in brain regions associated with the early stages of Alzheimer’s disease. They also exhibited greater white matter hyperintensities—an imaging marker linked to an increased risk of cognitive decline and dementia. In addition, they had reduced volumes in the frontal and occipital lobes, which are involved in planning, decision-making, and visual processing.
By contrast, prolonged sitting at work was not associated with the same brain changes. The researchers found that participants whose jobs involved mentally stimulating tasks while seated generally maintained better brain health, suggesting that the type of activity performed while sitting may be more important than the amount of time spent sitting.
Stronger Association in Men
The researchers noted that the relationship between frequent television viewing and brain changes was more pronounced in men than in women. They suggested that differences in sedentary behaviour, as well as biological and behavioural factors, may help explain this finding.
The research team also highlighted that mentally engaging activities such as reading, writing, problem-solving, and crafts may help strengthen what is known as cognitive reserve—the brain’s ability to withstand the effects of ageing and neurological disease.
Despite the findings, the researchers stressed that the study does not establish a direct cause-and-effect relationship between excessive television viewing and brain damage. Because the research relied on self-reported data, they emphasised that further studies are needed to better understand the nature of this association.
The researchers recommended limiting prolonged television viewing, taking regular breaks from sitting, and engaging in mentally stimulating activities to help maintain cognitive health as people age.
They also noted an important limitation of the study: it was observational, meaning it identified an association rather than proving that excessive television viewing causes brain shrinkage. In addition, participants did not undergo MRI brain scans at the beginning of the study, making it impossible to determine whether the observed brain changes developed during the 20-year follow-up period or were already present at baseline.
