This is the best way to protect against dementia

A healthy diet may be the best way to protect against dementia, a BMJ study suggests.

The research, involving almost 30,000 adults aged 60 and over, found lifestyle changes could make a significant reduction in the likelihood of disease.

Overall, age is the most significant factor.

Alzheimer’s disease affects an estimated one in six people over 80 and one in three by the age of 90, with the highest risk in those carrying genes linked to the disease.

The new study, carried out in China, examined the impact of six different lifestyle factors in lowering the chance of disease.

It found that overall, those with the healthiest lifestyles were almost 90 per cent less likely to develop dementia.

Having a varied and healthy diet - made up of at least seven of 12 food groups - was identified as the strongest protective factor. This was followed by “cognitive activity”, such as playing cards or reading, and regular physical exercise, such as a 20-minute brisk walk daily.

Other factors - such as regular social contact with family and friends, not smoking, and cutting out alcohol - also lowered the risk, but to a lesser degree.

Researchers said further studies were needed to establish exactly which lifestyle changes could make the most significant impact, or at what stage of life they made the most difference.

The China Cognition and Aging Study deemed a healthy diet as eating at least seven out of 12 food groups (fruits, vegetables, fish, meat, dairy, salt, oil, eggs, cereals, legumes, nuts and tea).

At the start of the study in 2009, memory function was measured using tests and people were checked for the APOE gene - the strongest risk factor gene for Alzheimer’s disease.

Follow-up assessments were then carried out over the next 10 years.

The people in the study were analysed according to how many healthy behaviours they had, with those with four to six healthy behaviours being put in the most favourable group.

Overall, those in the highest and medium groups were almost 90 per cent less likely to develop dementia and almost 30 per cent less likely to suffer mild cognitive impairment relative to those who were the least healthy.

The slower rate of memory decline seen in those with a healthy lifestyle was also seen in those with the APOE gene.

More research on lifestyle factors required

Writing in the British Medical Journal (BMJ), the team called for more research to see when particular lifestyle changes have the most impact.

“These results might offer important information for public health initiatives to protect older adults against memory decline,” they said.

The research was an observational study, meaning it could not prove cause and effect and relied on self-reporting about lifestyles.

Dr Susan Mitchell, head of policy at Alzheimer’s Research UK, said: “Too few of us know that there are steps we can all take to reduce our chances of dementia in later life. This is a well-conducted study, which followed people over a long period of time, adds to the substantial evidence that a healthy lifestyle can help to support memory and thinking skills as we age.

“While the genes we inherit play an important part in our chances of dementia as we age, importantly, this research found a link between healthy lifestyle and slower cognitive decline even in people who carry a key Alzheimer’s risk gene.

“There is no sure-fire way to prevent dementia - nobody brings it on themselves or is ever to blame for a disease like Alzheimer’s - the best we can do is improve our chances of living longer with better cognitive health,” she said.