Research reveals that the number of people with dementia in the UK is substantially lower than expected because overall prevalence in those aged 65 has dropped.

This study compares data collected from over 7000 people between 1989 and 1994, and 7796 people between 2008 and 2011, from the same geographical regions; Newcastle, Nottingham and Cambridgeshire. 

The results published online in The Lancet indicate that overall prevalence has gone down by 1.8 per cent to an estimated 6.5 per cent of the population. Using the current age profiles of the UK this corresponds to an estimated 670,000 people over the age of 65 living with dementia, a reduction of more than 20 per cent in the number of people projected to have dementia today compared with 20 years ago.

The two studies which involved Newcastle University ageing experts, provide the first estimate of the change in the number of people living with dementia in the UK. These new figures give a more accurate picture for those developing policies and planning healthcare services for dementia patients.

Health inequalities dementia link

Experts  from the initial MRC Cognitive Function and Ageing Study (CFAS) examined levels of dementia in the population and the latest figures from the follow up study, CFAS II, show that there is variation in the proportion of people with dementia across differing areas of deprivation, suggesting that health inequalities during life may influence a person’s likelihood of developing dementia.

Louise Robinson, Professor of Primary Care and Ageing at Newcastle University said: “Prevalence of dementia in the population is affected by a number of factors such as increased obesity and diabetes, known medically as vascular risk factors and increasing numbers of the very old by which we mean those over 80. Factors which can lower prevalence include successful primary prevention of vascular risk factors and increase early life education.

“We suspect that the current improvements are largely due to sustained improvements in primary prevention nationally and better, more effective evidence-based care for chronic conditions like diabetes.”

Prevalence of dementia in women remains higher than men, with 7.7 per cent of women over 65 estimated to have dementia, compared with 4.9 per cent of men. Although the overall prevalence of dementia has fallen, the prevalence of dementia among people living in care homes has increased, from 56 per cent of care home residents twenty years ago, to 70 per cent today.
 
The study was led by Professor Carol Brayne from the Cambridge Institute of Public Health at Cambridge University. She said: “This study provides compelling evidence of a reduction in the prevalence of dementia in the older population over two decades. Whether or not these gains for the current older population will be borne out in later generations would seem to depend on whether further improvements in primary prevention and effective health care for conditions which increase dementia risk can be achieved, including addressing inequalities.”
 
Professor Hugh Perry, Chair of the Neurosciences and Mental Health Board at the Medical Research Council who supported the studies, said: “This robust and comprehensive study gives us crucial information on the prevalence of dementia in the country. Of course we can’t assume that this reduction will be seen in future studies, therefore the need for us to find ways of preventing and treating dementia is as urgent as ever. We should be very much encouraged by the indication that there may be modifiable environmental factors that play a role in a person’s risk of developing dementia.”

Reference:  A two-decade comparison of prevalence of dementia in individuals aged 65 years and older from three geographical areas of England: results of the Cognitive Function and
Ageing Study I and II. Fiona E Matthews, Antony Arthur, Linda E Barnes, John Bond, Carol Jagger, Louise Robinson, Carol Brayne, on behalf of the Medical Research Council Cognitive Function and Ageing Collaboration. Published online in The Lancet alongside a Comment.

published on: 16 July 2013