Your dementia risk is highest if you sit for longer than this each day

Spending more than 10 hours a day sitting down in front of the TV or driving increases the risk of dementia, a study suggests.

Researchers have discovered the chances of developing the condition increase dramatically among adults who spend the majority of their day engaged in sedentary behaviours.

A team from the University of Southern California and the University of Arizona analyzed data on more than 50,000 British adults aged 60 and over.

Those who spent 10 hours a day sedentary were 8 per cent more likely to develop dementia. Meanwhile those who spent 12 hours a day sitting down were 63 per cent more likely to be diagnosed

They wore devices on their wrist for 24 hours a day over the course of a week. These devices monitored activity levels and could distinguish between sitting down and sleeping.

While watching TV or driving are common sedentary behaviors, others can include playing video games, using a computer, sitting while commuting or sitting at a desk at work.

The participants were followed for around six years, during which time 414 were diagnosed with dementia.

Analysis revealed that sitting down for 10 hours or more per day was linked to an increased risk of the disease.

Compared to those who spent closer to nine hours a day sitting down, those who spent 10 hours a day sedentary were 8 per cent more likely to develop dementia.

Meanwhile those who spent 12 hours a day sitting down were 63 per cent more likely to be diagnosed, while those who clocked up 15 sedentary hours a day were three times more likely.

Study author Professor Gene Alexander said: ‘We were surprised to find that the risk of dementia begins to rapidly increase after 10 hours spent sedentary each day, regardless of how the sedentary time was accumulated.

‘This suggests that it is the total time spent sedentary that drove the relationship between sedentary behaviour and dementia risk.

‘Importantly lower levels of sedentary behaviour, up to around 10 hours, were not associated with increased risk.’

The study, published in the journal Jama Network Open, also revealed the way sedentary behaviour is accumulated over the course of the day – for example a long period of sitting down followed by activity, or sitting down interspersed with standing up – had a similar link to dementia.

Professor David Raichlen, who also worked on the study, added: ‘Many of us are familiar with the common advice to break up long periods of sitting by getting up every 30 minutes or so to stand or walk around.

‘We found that once you take into account the total time spent sedentary, the length of individual sedentary periods didn’t really matter.’