Watching too much television increases the risk of dementia, academics have found.
People who watched television more than five hours a day had a 44 percent higher risk of developing the debilitating disease, according to a study of 400,000 people in the United Kingdom.
It was also associated with higher rates of stroke and Parkinson’s disease, and up to three hours of television viewing a day was found to be best for brain health. Researchers said the findings “suggest that spending a lot of time in front of the television is associated with an increased risk of several brain-related disorders.”
They analysed data from 407,000 people aged 37 to 73 from the UK Biobank project, of whom 40,000 had undergone a brain scan. None had any diagnosed brain disorders at the start of the study.
During the 13-year follow-up period, 5,227 developed dementia, 6,822 suffered a stroke and 2,308 were diagnosed with Parkinson’s.
Academics have found that people who watch more than five hours of television a day have a 44 per cent higher risk of developing dementia (file image)
Participants watched TV for an average of 2.7 hours a day. Those who watched TV for three to five hours were 15 percent more likely to develop dementia than those who watched TV for one hour or less.
For those who watched TV for more than five hours, the risk was 44 percent higher, along with a 12 percent higher risk of stroke and a 28 percent higher risk of Parkinson’s.
No increased risk was found for time spent in front of computers, probably because screen use is associated with “more mentally challenging behavior.”
The team from Tianjin Medical University in China also found that watching more than five hours of television was associated with less grey matter and smaller memory centres, both of which have been linked to brain diseases.
But it’s not clear exactly how TV watching produces such effects.
One theory is that sedentary behavior, with low levels of muscle activity and energy expenditure, leads to chronic inflammation and reduced blood flow to the brain.
Responding to the findings published in the Journal of the American Medical Directors Association, James Rowe, professor of cognitive neurology at Cambridge, said: “A couple of hours did not increase the risk. So enjoy your favourite TV show and then do something else.”