Dementia, lifestyle and the genome

A new study provides evidence that when it comes to dementia, it isn’t all in the genes…

It has long been established that dementia risk is influenced by both our genomes and our lifestyles. But a new study published in the Journal of the American Medical Association shows for the first time that adopting a healthy lifestyle can reduce the risk of getting dementia, even in people with a genetic predisposition to the condition.

Lifestyle matters

The research – conducted at the University of Exeter – found that people who don’t smoke and who exercise regularly, eat a balanced diet and drink responsibly are 30% less likely to suffer from dementia.

“We think there is a similar reduction in your risk of dementia associated with lifestyle, regardless of your genetic risk,” said Professor David Llewellyn, who led the study.

The research

Using data from UK Biobank, the researchers were able to follow almost 200,000 people of European ancestry (aged 60 or over) for eight years. Each participant was classified – using a polygenic score based on genomic variants identified by a previous GWAS study – as having a low, intermediate or high genetic risk of dementia.

The researchers also assigned each subject a ‘healthy lifestyle score’ based on four factors whose effects on dementia risk are well known: smoking, diet, exercise and alcohol consumption. Participants answered a questionnaire at the beginning of the study, and from their answers a weighted score was used to categorise them as having favourable, intermediate or unfavourable lifestyles.

Over the course of eight years, 1.2% of those with the highest genetic risk developed dementia compared with 0.6% of those with the lowest. When looking at the data by lifestyle groups, 0.8% of those who reported favourable lifestyles developed dementia, compared with 1.2% of the people with unfavourable lifestyles.

The researchers were able to show that – after allowing for other factors such as age, sex and socioeconomic status – the two effects were completely independent of each other.

What does it mean in practice?

This research offers an empowering message that has been broadly welcomed by dementia charities.

Dr Carol Routledge from Alzheimer’s Research UK highlighted a recent survey, which showed that only 34% of adults thought it was possible to reduce the risk of developing dementia. She said: “Sadly, as genetics still plays an important role in influencing the risk of Alzheimer’s, there will always be people who address many or all of these lifestyle factors and still develop the disease. While we can’t change the genes we inherit, this research shows that changing our lifestyle can still help to stack the odds in our favour.”

Dr Fiona Carragher of the Alzheimer’s Society shared the concerns of adults who have already lost a parent to dementia and fear that they will develop it too: “Dementia is the most feared condition in the over 50s. Reassuringly, this study suggests that, even if you have a high genetic risk of developing dementia, adopting risk-reducing techniques like eating well, not smoking, drinking less alcohol and keeping active can significantly reduce your risk of developing dementia.”