By Maureen Salamon
MONDAY, July 15 (HealthDay News) -- As Americans increasingly delay retirement, a new French study indicates this scenario may have a silver lining: a lower risk of developing Alzheimer's disease.
Researchers analyzing health and insurance records of more than 429,000 self-employed workers found a 3 percent reduction in dementia risk for each extra year at the age of retirement. Workers evaluated had been retired for an average of more than 12 years, and 2.65 percent of the group had dementia.
"There's increasing evidence that lifestyle factors such as exercise, mental activities, social engagement, positive outlook and a heart-healthy diet may reduce the risk of developing Alzheimer's disease and other forms of dementia," said Dr. James Galvin. "Now we can add staying in the workforce to this list of potential protective factors."
Galvin, director of the Pearl Barlow Center for Memory Evaluation and Treatment at the NYU Langone School of Medicine, was not involved with the new research.
The study, led by Carole Dufouil, director of research in neuroepidemiology at the French National Institute of Health and Medical Research, is scheduled to be presented Monday at an Alzheimer's Association conference in Boston. Research presented at scientific conferences typically has not been peer-reviewed or published and results are considered preliminary.
About 5.2 million Americans have been diagnosed with Alzheimer's disease, which is the sixth leading cause of death in the United States, according to the Alzheimer's Association.
Americans are increasingly putting off retirement, especially those in the middle class. According to a 2012 Wells Fargo survey of 1,000 Americans earning less than $100,000 annually, almost one-third said they'd need to work until age 80 to live comfortably in retirement.
But Dufouil's research, which linked health and pension databases of self-employed workers who were retired as of 2010, puts a positive spin on that choice. In study background materials, she said the data is in line with the "use it or lose it" hypothesis of brain health. The study showed an association between higher retirement age and lower dementia risk, but not a cause-and-effect relationship.
One Alzheimer's disease expert was not surprised by the new findings.
"There seems to be growing evidence that staying cognitively [mentally] active is really important to reducing a person's risk, and perhaps professional activity may be one of those cognitive activities," said Heather Snyder, director of medical and scientific operations for the Alzheimer's Association, based in Chicago. "What we know is that things that promote lifelong learning seem to be beneficial. But that may mean different things for different people . . . and exactly what that is, we can't define at this point in time."
For his part, Galvin noted several caveats to keep in mind when interpreting the study's meaning. First, he said, self-employed workers may be inherently different than company-employed workers, with differences in skill sets, work environment, stress and social mobility that might affect the study's results.
Also, the prevalence of dementia was based on a review of either an existing dementia diagnosis or prescription for dementia-related medication, he noted.
"There is no way of knowing about those individuals who did not seek medical attention, did not have access to health care or who were not properly diagnosed," Galvin added. "Nonetheless, the study supports the concept that keeping oneself mentally, physically and socially active over the span of a lifetime may have important effects on both physical and mental health."