|
MINNEAPOLIS, June 29 (UPI) -- Errors in memory and thinking on tests may show the potential to develop Alzheimer's disease up to 18 years before symptoms are visible and it can be diagnosed. An 18-year study found that one unit lower in score on the test 13 to 18 years before the final assessment of participants was associated with 85 percent greater chance of developing Alzheimer's, researchers said. "A general current concept is that in development of Alzheimer's disease, certain physical and biologic changes precede memory and thinking impairment," said Kumar B. Rajan, Ph.D., an assistant professor at Rush University Medical Center in Chicago, in a press release. "If this is so, then these underlying processes may have a very long duration. Efforts to successfully prevent the disease may well require a better understanding of these processes near middle age." Every 3 years for 18 years,2,125 Chicago residents with an average age of 73 tests were given memory and thinking tests. None of the participants had the disease at the beginning of the study. During the study, 23 percent of African-Americans and 17 percent of European-Americans developed Alzheimer's. Participants with lower test scores during the first year of the study were found to be 10 times more likely to be diagnosed with Alzheimer's, and the odds increased by 10 for each unit that scores were lower than average. "The changes in thinking and memory that precede obvious symptoms of Alzheimer's disease begin decades before," Rajan said. "While we cannot currently detect such changes in individuals at risk, we were able to observe them among a group of individuals who eventually developed dementia due to Alzheimer's." Nearly two-thirds of Americans with Alzheimer's disease are women, and now some scientists are questioning the long-held assumption that it's just because they tend to live longer than men. What else may put woman at extra risk? Could it be genetics? Biological differences in how women age? Maybe even lifestyle factors? Finding out might affect treatments or preventive care. One worrisome hint is that research shows a notorious Alzheimer's-related gene has a bigger impact on women than men. "There are enough biological questions pointing to increased risk in women that we need to delve into that and find out why," said Maria Carrillo, chief science officer for the Alzheimer's Association. Last month, the association brought 15 leading scientists together to ask what's known about women's risk. Later this summer, Carrillo said it plans to begin funding research to address some of the gaps. "There is a lot that is not understood and not known. It's time we did something about it," she added. A recent Alzheimer's Association report estimates that at age 65, women have about a 1 in 6 chance of developing Alzheimer's during the rest of their lives, compared with a 1 in 11 chance for men. The tricky part is determining how much of the disparity is due to women's longevity or other factors. "It is true that age is the greatest risk factor for developing Alzheimer's disease," said University of Southern California professor Roberta Diaz Brinton, who presented data on gender differences at a meeting of the National Institutes of Health this year. But, she said, "on average, women live four or five years longer than men, and we know that Alzheimer's is a disease that starts 20 years before the diagnosis." That's how early cellular damage can quietly begin. Brinton researches if menopause can be a tipping point that leaves certain women vulnerable. However it starts brewing, there's some evidence that once Alzheimer's is diagnosed, women may worsen faster; scans show more rapid shrinkage of certain brain areas. But gene research offers the most startling evidence of a sex difference. Stanford University researchers analyzed records of more than 8,000 people for a form of a gene named ApoE-4, long known to increase Alzheimer's risk. Women who carry a copy of that gene variant were about twice as likely to eventually develop Alzheimer's as women without the gene, while men's risk was only slightly increased, Stanford's Dr. Michael Greicius reported last year. It's not clear why. It may be in how the gene interacts with estrogen, Brinton said. Amy Shives, 57, of Spokane, Washington, recalls when her mother began showing symptoms of Alzheimer's. But it wasn't until after her own diagnosis a few years ago that Shives looked up the gender statistics. "That was alarming," said Shives, who is in the early stages of Alzheimer's, which struck at a younger-than-usual age and forced her retirement as a college counsellor. "The impact on our lives and that of our families is extraordinary." She points to another disproportionate burden: About 60 per cent of caregivers for Alzheimer's patients are women.
|
