KEEPING active, not smoking and speaking more than one language are among the traits that keep the brain healthy into old age, according to a review of a long-running ageing study.

The findings were presented as more than 400 people now in their 80s and 90s reunited in Edinburgh exactly 70 years to the day since they sat an intelligence test aged 11 at school which has underpinned the research.

The participants, known as the Lothian Birth Cohort, were photographed together on the Mound during an event held at the General Assembly Hall marking their contribution to the understanding of the ageing brain. The study has provided insight into how a person’s thinking power changes over their lifetime.

The event also outlined the findings of a review into to study so far, which will be published in the journal Psychological Medicine later this month.

The review concludes that the study has pointed to genetics, being in good physical condition, being active, being more intelligent in childhood, speaking more than one language, not smoking, and having more education as factors which contribute to healthy brain ageing.

However, the review stressed that each only offered "marginal gains", not a "magic bullet" to prevent mental decline. Genes "account for about 24 per cent of change in general cognitive ability between youth and old age", but the intelligence differences identified at 11 remain "relatively stable" throughout life - even into a person's 80s and 90s. It adds: "Intelligence differences in youth are the largest contributor to cognitive ability differences in older age."

The event yesterday [sun] was also attended by the scientists from Edinburgh University who have spearheaded the research.

Professor Ian Deary, a psychologist at Edinburgh University's Centre for Cognitive Ageing, who started and still leads the study, said: “These anniversaries of Scotland’s national intelligence testing in June 1932 and 1947 are a lovely way to bring these special individuals together to celebrate what they have contributed to ageing science.

"From the start of the Lothian studies, almost 20 years ago, I’ve made sure that the participants see their basic results before we report them. Of course, it’s also a happy occasion in which to have a good blether and to swap the pleasures and pains of growing older.”

The study is split into two groups according to the year of their birth - the Lothian Birth Cohort 1936, now aged 81 and the Lothian Birth Cohort 1921, now aged 96. Both groups went on to sit an intelligence test at primary school in 1932 and 1947 respectively, as part of the Scottish Mental Survey.

Researchers have used those original results combined with ongoing cognitive and lifestyle assessments over the past decade to evaluate why some people’s thinking skills, brains and bodies age better than others.

As well as regularly resitting the school mental test both groups have undergone medicals every three years, including blood and ultrasound tests, brain scans and retina examinations in older age, and checks such as memory tests. They have also reported on their diet, social background, activity and feelings of wellbeing.

Tom Wright, Group Chief Executive of Age UK, which has funded the Lothian Birth Cohort 1936 study, said: “We are very proud to be funding this unique project which is proving to be an invaluable source of information to help us understand how and why our thinking skills change with age.

“As we live for longer, we all want to age as well as we can and keep our mental sharpness for as long as possible."