Sitting all day at a desk or all evening on your sofa may make your brain shrink and increase the risk of Alzheimer’s, a study suggests.
Measurements of a key part of the brain found people who were active had a larger brain region important in forming memories. But couch potatoes brains’ were thinner in this key area.
A study by the University of California at Los Angeles asked 35 people aged 45 to 75 about their physical activity levels, and how many hours a day on average they had spent sitting over the previous week. The researchers then gave them a brain scan, paying particular attention to the part of the brain called the medial temporal lobe (MTL), a brain region involved in forming new memories. The researchers found that sedentary people had a thinner MTL. This was true even if they had very high levels of activity alongside their hours of sitting in one spot.
In the study, the average person was found to sit down for seven hours 12 minutes a day. The authors are at pains to stress that they have not proved sitting causes thinner brain structures, but that they have found more hours spent sitting was associated with thinner regions.
Writing in the journal PLOS ONE, the authors said that their research found exercise did not counterbalance long periods of sitting. They conclude: ‘Physical activity, even at higher levels, is not sufficient to offset the harmful effects of sitting for extended periods of time.’ The researchers suggest that sitting for long periods leads to a decrease in blood flow to the brain, which in turn reduces the numbers of new cells that can be formed in the brain, and lead to worse brain health.