The way in which a person’s mind ages, is largely down to lifestyle factors, not genetics, a study has shown.

Researchers found genetic factors only account for 24% of changes in intelligence, suggesting environmental factors have the biggest influence on whether a person’s mind remains sharp in old age.

The study, conducted by research teams in the UK and Australia, combined DNA analysis with data from around 2,000 participants who were asked to take intelligence tests at age 11, and again aged 65 to 79.

The study, funded by the charity Age UK, is published in the journal, Nature.

Scientists studied more than half a million genetic markers and found that many of the genes that affect intelligence in childhood also influence intelligence in old age.

Researcher Professor Ian Deary, from the University of Edinburgh, said, as reported by the Press Association: "Until now, we have not had an estimate of how much genetic differences affect how intelligence changes across a lifetime. These new findings were possible because our research teams were able to combine a range of valuable resources.

"The results partly explain why some people's brains age better than others. We are careful to suggest that our estimates do not have conventional statistical significance, but they are nevertheless useful because such estimates have been unavailable to date."

Australian co-author Professor Peter Visscher, from the University of Queensland, said: "Unique data and new genome technologies combined with novel analysis methods allowed us to tackle questions that were not answerable before.

"The results also strongly suggest how important the environment is helping us to stay sharp as we age. Neither the specific genetic nor environmental factors were identified in this research. Our results provide the warrant for others and ourselves to search for those."

Professor James Goodwin, from the charity Age UK, which funded the study, said:

"This research is extremely exciting as it provides a greater understanding about why mental abilities change throughout our lifetime. It is also incredibly positive as it suggests that we can have a real influence on how our brain ages through our lifestyle and other external factors.

"The key now is to establish which lifestyle and environmental factors are most important so that we are able to do all we can to maximise our chances of ageing well."

According to a recent New York University study, virtual reality exercise slows down mental and physical decline in the elderly.

Age UK recommend the following lifestyle tips for better ageing fo the mind and body:

Go Mediterranean
"Try to eat a Mediterranean diet with plenty of fruit and veg, plant oils, wholegrains, oily fish, nuts, beans and pulses, limited animal fats and small amounts of low-fat dairy and lean meat.

"This has been shown to keep your heart healthy and may also reduce the risk of developing Alzheimer’s," says British Dietetic Association spokesperson Sian Porter.

Do daily stretches
"A daily stretch will improve your flexibility and posture," says fitness expert Gina Hemmings.
"Sit in a chair and bend forwards to stretch your spine, then stand and stretch your arms over your head, out to the side and behind you."

Cut back on salt
Excess salt increases the risk of high blood pressure and stroke. Check labels for the salt content, particularly in processed meats, ready meals, savoury snacks and biscuits.

Be positive
Research shows that older people who have a positive attitude to ageing, and who work with the changes it brings, tend to have better health and live longer than those who see only the negatives. Take up activities in your local area to meet new people.

Age UK supports more than 85 Friendship Centres across England and works with a network of 600 independent forums of older people.

Get sufficient sleep

The right amount of good-quality sleep reduces your risk of depression, lowers inflammation and improves heart health.