Fall in rate of dementia eases ageing fears Dementia rates could fall: Experts on ageing say the studies suggest dementia rates would decrease as the population grows healthier and better educated. A new study has found that dementia rates among people aged 65 and older in England and Wales have plummeted by 25 per cent over the past two decades, to 6.2 per cent from 8.3 per cent, a trend that researchers say is probably occurring across developed countries and that could have major social and economic implications. Another recent study, conducted in Denmark, found that people in their 90s who were given a standard test of mental ability in 2010 scored substantially better than people who reached their 90s a decade earlier. The two studies, both published in The Lancet, soften alarms sounded by advocacy groups and some public health officials who have forecast a steadily rising population of baby boomers with the same odds of getting dementia as older people now, as well as exploding costs to care for them. And experts on ageing say the studies confirm something they long suspected but lacked good evidence to prove: that dementia rates would fall as the population grew healthier and better educated. Dallas Anderson, an expert on the epidemiology of dementia at the National Institute on Aging, the principal funder of dementia research in the United States, said the new studies were "rigorous and are strong evidence." Major clinical trials of drugs to treat Alzheimer's have failed. And a recent analysis by the RAND Corporation - based on an assumption that dementia rates would remain steady - had concluded that the number of people with dementia would double in the next 30 years, as would the costs to care for them. Maria Carrillo, vice-president of medical and scientific relations at the Alzheimer's Association, an advocacy group, warned that the British paper had a methodological flaw and that the Danish work might reflect the fact that people there were generally healthier than those in the US. The studies assessed dementia, which includes Alzheimer's disease but also other conditions. Richard Suzman, the director of behavioural and social research at the National Institute on Aging, said it was not possible to know from the new studies whether Alzheimer's was becoming more or less prevalent. "Other forms of dementia could be going down, and Alzheimer's could be going up, for all I know," he said. The British researchers took advantage of a large study that between 1984 and 1994 tested for dementia in 7635 people aged 65 and older, selected randomly in England and Wales. Then, between 2008 and 2011, the researchers assessed a similar randomly selected group of people living in the same areas. Ms Carrillo said she questioned the data because so many subjects had declined to be assessed: the researchers assessed 80 per cent of the group it approached in the first round and 56 per cent of those approached in the second. The researchers said they addressed this concern by analysing to see if the refusals might have skewed the results and decided they had not.