Improving cognitive ability through education and health may cut dementia risk

The study by Cambridge University researchers Dr David Llewellyn and Dr Fiona Matthews and the Medical Research Council Cognitive Function and Ageing Study shows a small but significant improvement in elderly people's mental abilities over the last two decades which researchers believe could be down to raising the age of compulsory education, reductions in the number of elderly people smoking and other health developments.

Published in the journal Aging, Neuropsychology and Cognition this month, the study could help to predict future numbers of elderly people who will develop dementia with greater accuracy.

The researchers compared the results of a representative sample of more than 9,000 people over 65 whose mental faculties were tested in 1991 with those of over 5,000 people in 2002. The test, an animal naming test which is among the standard ones used for detecting early signs of dementia, was restricted to those whose first language was English and excluded non-white participants and those in nursing homes.

The researchers also compared the results of 680 East Cambridgeshire residents aged between 60 and 69 who were tested in 1991 with an independent cohort of 600 people tested in 1996.

The tests showed a small but potentially significant increase in the number of words a minute people used when asked to list words associated with animals. The results were similar across the general sample and the East Cambridgeshire sample.

In the 2002 study, the sample was slightly older and more prone to diseases such as hypertension and diabetes mellitus. In both samples, results were lower for older people, women and the less educated. The only group which showed no improvement between 1991 and 2002 were the least educated.

Poor cognitive function is associated with the onset of dementia, disability, institutionalisation and death. It has been predicted that around 3.1% of people aged over 60 worldwide will suffer from dementia with significant increases expected as the world's population ages. The results of this new study tally with those coming out of the US.

Writing in Aging, Neuropsychology and Cognition, Dr Llewellyn, a research associate in the Department of Public Health and Primary Care, and Dr Matthews, a statistician in the MRC Biostatistics Unit, say: "Our findings are important because detrimental influences on cognitive health appear to have been cancelled out by greater levels of education, fewer heart attacks, increased prescription of antihypertensive medications, decreased smoking and improvements in other unmeasured factors associated with cognition, such as early life nutrition. This is significant as these findings can be used to help refine future projections of cognitive function in aging industrialised populations."