A study of roughly 1,700 adults links heavy television viewing in midlife to smaller brain volumes and greater white matter damage decades later. The research suggests the type of sedentary activity matters more than sitting alone. Men showed stronger associations in the findings.
Participants in the Atherosclerosis Risk in Communities study reported their television habits at an average age of 53 between 1987 and 1989. More than 20 years later, those who watched television very often displayed reduced volumes in memory-related regions as well as the frontal and occipital lobes on MRI scans.
They also had larger volumes of white matter hyperintensities, markers linked to small vessel disease and cognitive decline. These patterns held after adjustments for physical activity, diabetes, body mass index, smoking and alcohol use.
In contrast, adults who spent long hours seated at work showed larger frontal and occipital lobes and fewer white matter changes. The differences appeared more pronounced in men than in women.
"For years we've focused on how much people sit," said David Raichlen of USC Dornsife. "Our findings suggest we should also pay attention to what they're doing while they're sitting."