A healthy lifestyle that includes regular exercise, a balanced diet, no smoking and watching alcohol consumption can reduce the risk of dementia – even for people with a genetic predisposition to such conditions – say the researchers.
Recent data suggests that 850,000 people with dementia live in the UK, and that this is the main cause of women's death in England. Many studies indicate that lifestyle changes can reduce the risk of such diseases. A recent report suggests that one-third of cases can be prevented by combating factors such as exercise, blood pressure, hearing and diet. In May, the World Health Organization published guidelines for a healthy lifestyle.
However, it was not clear whether such measures could have the same effect on those whose genes predispose them to dementia. Now experts say yes.
"We believe that there is a similar reduction in the risk of lifestyle dementia, regardless of the genetic risk," said Prof. David Llewellyn from Exeter University, who conducted the research.
Llewellyn said the study also emphasized that high genetic risk or dementia in the family did not cause this condition to occur.
Writing in the journal of the American Medical Association, Llewellyn and his colleagues describe how they came to their conclusions by examining the data collected as part of a broader research project called UK Biobank, with almost 200,000 people of European descent aged 60 or older at the beginning he had dementia or cognitive problems.
The team divided participants into five equal groups based on a combination of nearly 250,000 genetic variants related to Alzheimer's disease in people of European descent. On this basis, three categories of low, medium and high genetic risk for dementia were developed – the first and the second included 20% of participants.
Researchers also looked at the lifestyle of the participants and the four key factors associated with reduced risk of dementia: met the recommended exercise guidelines, did not smoke, ate different food groups with small processed meat and plenty of fruit and fish and drunk or less standard alcoholic beverages a day for women and two or less for men. Participants received an evaluation that reflects the overall "health" of their lifestyle.
The team followed the participants for about eight years, during which time 1769 people – less than 1% of participants – developed some form of dementia.
The results show that the incidence of dementia was higher in the group with the highest genetic risk compared to the lowest: 1.2% and 0.6%, respectively. A lower percentage of people with a healthy lifestyle developed dementia than unhealthy people: 0.8% and 1.2%.
Most importantly, these trends have appeared independently of each other. When the team took into account factors such as age, sex and socioeconomic status, it turned out that a healthy lifestyle is associated with about 30% lower risk of dementia compared to an unhealthy lifestyle, regardless of high or low genetic predisposition.
Although the impact may seem small, the team concluded that the participants were younger and would continue to follow the group to investigate the relationship between lifestyle factors and the risk of dementia when people in age and more cases of dementia appeared.
The study has limitations, including that lifestyle data was collected at one time and reported on its own, and they do not prove that a healthier lifestyle leads to a reduction in the risk of dementia. The study concerned only those of European origin, while some cases of dementia could be omitted.
Professor Gill Livingston, an expert on Dementia Prevention at University College London who was not involved in the study, noted that the study involved a small number of lifestyle-related factors and that participants had a healthier overall lifestyle than the general population.
Nevertheless, she welcomed the study. "This is a very important document, with the clear message that a healthy lifestyle reduces the risk of dementia, no matter what genes are," she said.