Nearly three-quarters of dementia cases could be prevented, a study shows.
Researchers looked at a huge list of 210 factors that could be associated with a greater risk of dementia.
They found among them 62 preventable probable causes of the condition.
These causes are estimated to be responsible for 47 to 73 percent of dementia cases.
The knowledge could save hundreds of thousands of people from a devastating diagnosis, with dementia currently estimated to affect more than 900,000 people in Britain.
An unhealthy lifestyle, such as being sedentary, was found to contribute to more preventable cases of dementia
Watching too much television and sleeping less than seven or more than nine hours were among the lifestyle problems linked to a higher risk of dementia, which people may be able to change.
In fact, it was found that an unhealthy lifestyle contributes to more preventable cases of dementia (nearly 17 percent) than a person’s medical history.
Interesting new findings from the study are that feeling tense or ‘very tense’ and rarely being able to confide in others can increase your risk of dementia.
But the most important of the 62 factors are things like frailty, measured by a weak grip, and medical problems such as diabetes, disability or having had a previous stroke.
These medical risks can also be reduced through a healthier lifestyle, such as regular exercise and a healthy diet.
The study examined more than 344,000 Britons, who were questioned in detail about their lives before the UK Biobank health survey and were followed for an average of fifteen years.
The 62 likely preventable causes of dementia were found because they were more commonly seen among the 4,654 study volunteers who developed the condition.
Professor David Smith, co-author of the study from the University of Oxford, said: ‘There is still a view among many people that the possibility of developing dementia is an inevitable part of growing older.
‘But these results show that dementia is much more preventable than previously thought.
‘That is extremely important because, as there are no very effective treatments for dementia, preventing it should be our focus in the first place.’
The research, published in the journal Nature Human Behavior, shows that lifestyle, including poor sleep, not being a member of a sports club or gym, and insufficient water intake, can cause 16.6 percent of dementia cases.
Medical history, especially disability, stroke, diabetes and depression, could account for 14 percent of cases.
Socioeconomic status, such as being unemployed or having a lower income, which can make healthy choices more difficult, is estimated to be responsible for 13.5 percent of dementia cases.
The study also concludes that the risk of dementia can be reduced by physical measures, such as a stronger grip, and can be influenced by social and psychological factors such as loneliness and isolation.
People’s local environment, such as green space, was seen as less important, and early life, such as whether you were breastfed as a baby, was not linked to dementia.
The study found that people with a poor lifestyle may have a 62 percent higher risk of developing dementia than those with a good lifestyle.
Improving all six categories – lifestyle, medical history, physical measures, socio-economic status, social and psychological factors and local environment – from poor to good or average levels could prevent an estimated 47 percent of dementia cases.
By bringing them all to a good level, it was calculated that 73 percent of cases could be prevented.
The results were seen for people regardless of their age or gender, and remained similar even when people’s genetic risk of dementia was taken into account.
Patrick Holford, CEO of the charity Food for the Brain, which offers a free online questionnaire on the risk of dementia, said: ‘We already know that a healthy lifestyle can massively reduce the risk of dementia, and as this condition is not reversible, really need to take the right steps in middle age to maintain their cognitive function.
‘Dementia is a completely preventable disease.’