The proportion of life spent in good fit, healthy lives are increasing in England, even as life expectancy continues to rise.
The research compared two identical surveys, 20 years apart, that measured the health of people aged 65 or older in Cambridge, Newcastle and Nottingham.
The data, collected in 1991 and 2011, involved more than 15,000 responses.
Experts say the findings are encouraging, but warned they suggest health inequalities remain in the UK.
New health threats – such as obesity – may have an impact on wellbeing in the future, which needs investigating, say the researchers.
The work, part-funded by the Medical Research Council and published in The Lancet, looked at three measures of good health:
time free from cognitive impairment (dementia)
life without disability
In 2011, men spent nearly four more years and women about three more years in “self-reported” good health compared with the respondents in the 1991 survey.
The chance of having dementia also appeared to be reduced in the 2011 group – men and women enjoyed about four more years free of any cognitive impairment compared with those surveyed in 1991.
Life without disability gains between 1991 and 2011 were smaller – 2.6 years for men and half a year for women, on average – and there was a mixed picture. While severe disability became less common between 1991 and 2011, milder disability increased.
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The researchers say the milder disability figures might be explained by rising rates of obesity and arthritis.
But, overall, they say their findings are positive.
Lead researcher Prof Carol Jagger, from Newcastle University, said: “Brain health has improved over the 20-year period. We’re not entirely sure why.”
Although, as individuals, people may be living more years without cognitive impairment, Prof Jagger said, it was important to remember the number of cases of dementia in the UK was still rising because of an ageing population – there were more elderly people living in the country, meaning more “at risk”.
“Our findings have important implications for government, employees and individuals with respect to raising the state pension age and extending working life,” she said.
“It is also necessary for community care services and family carers who predominantly support those with mild to moderate disability to enable them to continue living independently.”
Caroline Abrahams, charity director at Age UK, said: “Real improvements in older peoples’ health are a real cause for celebration and demonstrate the continuing importance of supporting people to age well, especially through the provision of good quality health and social care services.”
“However, we know that health inequalities are still deeply entrenched across the UK and with a growing older population, particularly of those aged over the age of 85, there is still much more work to do to help every older person have a healthier and happier later life.”