The finding has been revealed following five years of tests on more than 700 volunteers in Chicago, with an average age of 80.
The participants were part of the Rush Memory and Aging Project, a longitudinal study of more than 1,200 older people.
Of the group 90 developed Alzheimer's disease and the researchers noted that in old age a cognitively active person was 2.6 times less likely to develop dementia and Alzheimer's disease.
They believe the findings may be used to help prevent Alzheimer's disease.
Dr. Robert S. Wilson from the Alzheimer's Disease Center at Rush University Medical Center says Alzheimer's disease is among the most feared consequences of old age and poses enormous public health problems which are expected to increase during the coming decades.
He says the study highlights the urgent need for strategies to prevent the disease or delay its onset.
The study also found activities during old age, such as visiting a library or attending a play, was associated with reduced risk of mild cognitive impairment, a transitional stage between normal aging and dementia, and less rapid decline in cognitive function.
Other studies have suggested that keeping socially engaged and eating a Mediterranean diet also help prevent the disorder.
This research is published in Neurology, the medical journal of the American Academy of Neurology and was supported by grants from the National Institute on Aging and the Illinois Department of Public Health.
There were three key findings from the study first, the benefit of switching to a healthy lifestyle past age 45 became evident even in the 4-year, short-term follow up; second, the beneficial impact of the changes occurred despite the relatively modest changes in health habits; and third, the healthy lifestyle was beneficial when compared to all persons with three or fewer healthy habits, not just in comparison to people with none or one habit. People adopting only three healthy habits experienced lower mortality but not fewer CVD events over the same period.
The authors found that only 8.5% of middle-aged adults practice these four behaviors and only 8.4% newly adopt such a lifestyle past age 45. Further, men, African-Americans, and individuals with less than college education, lower income, or a history of hypertension or diabetes are less likely to adopt a healthy lifestyle past age 45, and are therefore at greater risk of mortality and cardiovascular disease.
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