“Turn off the TV, it will rot your brain!” — this phrase has echoed everywhere for decades. While the word “rot” might be a bit strong, researchers are discovering that there may be some truth to the claim overall.
A study recently published in the journal Alzheimer’s & Dementia found that individuals who watched television very frequently during middle age later experienced a reduction in the volume of brain regions associated with memory, a decrease in the size of the frontal and occipital lobes, as well as damage to white matter linked to aging, stroke risk, cognitive decline, and dementia.
“For many years, we’ve primarily focused on how much time people spend sitting. Our results suggest that we should also pay attention to what they do while seated,” says co-author of the study, Professor David Raichlen from the University of Southern California.
The findings are not solely explained by the sedentary nature of TV watching. The study revealed that other forms of sedentary activity do not share the same association, indicating that what a person does while sitting may matter much more than previously thought.
Researchers analyzed data from approximately 1,700 adults with an average age of 53, who participated in the Atherosclerosis Risk in Communities (ARIC) study between 1987 and 1989. The ARIC study is a long-term investigation of the U.S. population focused on understanding cardiovascular and brain health.
Participants were asked how often (on a scale from “never/rarely” to “very often”) they watched television during their free time and how much time they spent sitting during the workday.
More than two decades later, the study participants underwent brain MRI scans. Compared to individuals who reported “never” or “rarely” watching TV, those who watched TV “very often” showed extensive structural differences throughout the brain.
Researchers observed a smaller volume in regions linked to early signs of Alzheimer’s disease, and a greater volume of hypertensive white matter changes, which are indicators of damage to small blood vessels in the brain associated with cognitive impairment and dementia. These participants also had a smaller volume of the occipital and frontal lobes, areas involved in visual processing and executive functions.
The differences persisted even after the researchers accounted for factors such as physical activity, diabetes, body mass index, smoking, and alcohol consumption.
It is worth noting that the researchers relied on self-reported data regarding television consumption, which may be less accurate than tracking viewing time. Additionally, the study participants did not undergo initial MRI scans. Future studies could start with a baseline MRI to more precisely demonstrate changes over time.
Those who reported spending a lot of time sitting at work had larger frontal and occipital lobes, as well as a reduced volume of hypertensive white matter lesions, indicating better brain health compared to those who sat while watching TV. According to the study authors, this may be linked to the intellectually stimulating nature of many desk jobs.
Men proved to be particularly vulnerable to these changes. When the MRI results were analyzed by sex, researchers found that most of the brain changes associated with both TV watching and sedentary work were observed in men.
The findings indicate that further research is still needed on this complex topic. However, we may eventually see a different approach to healthy lifestyle recommendations regarding sedentary behavior. For instance, instead of simply advising patients to move more, doctors might recommend reducing time spent watching TV and incorporating cognitively active activities into periods when they are sitting.
“We often urge the public not to spend too much time sitting, but experts may need to broaden this recommendation to include the type of activity performed while seated, as it appears to have a different impact on brain health,” says co-author of the study Nathan Fether from the University of Southern California.
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