The decade-long study of Chinese adults over the age of 60, published in The BMJ, showed that the benefits of healthy living were even seen in those with a gene making them genetically susceptible to Alzheimer’s disease.

Carriers of the apolipoprotein E (APOE) gene - the strongest known risk factor for Alzheimer’s and related dementia - saw a slowing in memory loss thanks to healthy living such as staying teetotal.

After taking into account other health, economic and social factors, the researchers found that each individual healthy behaviour was associated with a slower than average decline in memory over 10 years.

Study lead author Professor Jianping Jia said: “A healthy diet had the strongest effect on slowing memory decline, followed by cognitive activity and then physical exercise.

He said the research was observational so can’t establish cause, but it was a large study with a long follow-up period, allowing for evaluation of individual lifestyle factors on memory function over time.

Prof Jia, of the National Centre for Neurological Disorders in Beijing, added: “These results might offer important information for public health initiatives to protect older adults against memory decline.”