Everyone has heard that TV rots the brain. According to new research, that might not be quite as far-fetched as it sounds.
Older people who had watched TV “very often” in midlife had reduced volume in the brain regions linked to memory, smaller frontal and occipital lobes, more age-related damage in white matter and a higher risk of stroke, cognitive decline and dementia. In the study, other types of sedentary behavior did not carry the same risk of reduced brain structures. The study was published in Alzheimer’s & Dementia.
“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,” said the senior author of the study, Prof. David Raichlen of USC.
The study used data gathered between 1987 and 1989 from about 1,700 adults who had an average age of 53. They were asked about sitting at work and their TV habits. More than 20 years later, the participants had MRIs. People who had said they watched TV “very often” had widespread structural differences in their brains. The people who had said “never” or “seldom” did not.
The study participants didn’t have a baseline MRI in the ‘80s. They also self-reported their TV habits. But the differences between the TV-watchers and non-watchers remained when the researchers accounted for factors like exercise, blood sugar concerns, BMI, smoking and alcohol use.
Sitting by itself didn’t appear to cause problems. People who sat more during the workday had larger frontal and occipital lobes. They also have healthier white matter. The researchers thought that could be because people who sit at work are more likely to be doing mentally taxing jobs rather than physically difficult jobs.
Mentally challenging activities are like workouts for the brain. When a person is writing, problem solving, planning or remembering things, electrical firings occur to complete the task. Watching TV is a passive activity that requires less activity in the brain. Like a muscle atrophies when not being used, that could lead to structural changes in the brain over time.
Men were found to be more vulnerable to the brain changes than women. The disparity may come down to cardiovascular differences, hormonal differences and how men and women spend their leisure time. The researchers thought that the women may have watched more mentally taxing TV or paired it with another, healthier habit not noted in the original questions.
“We frequently encourage the public not to spend too much time sitting down, but experts may want to expand that recommendation to encompass the activities done while sitting, since those seem to have distinct impacts on brain health,” said study corresponding author Natan Feter.
