Mexican-Americans' memories may worsen earlier than whites'
By Mary Ann Roser, Austin American-Statesman/MCT January 6, 2014, 12:07 am TWN
AUSTIN, Texas--New research suggests that Mexican-Americans might develop memory problems that could lead to Alzheimer's disease as much as a decade earlier than non-Hispanics.
If the work is confirmed by additional studies, Mexican-Americans with mild cognitive impairment, or MCI, could be identified earlier and put into treatment sooner, said Sid O'Bryant, the study's leader.
His team has done other work that suggests Mexican-Americans get MCI earlier, but "I would never have expected there to be that much of an age difference," said O'Bryant, an associate professor and interim director of the Institute for Aging and Alzheimer's Disease Research at the University of North Texas Health Science Center.
Little research has been done on MCI and Mexican-Americans, who make up 65 percent of the nation's Hispanic population. The study — recently published in the journal Alzheimer's & Dementia — included researchers from the University of Texas Southwestern Medical Center in Dallas and the UT Health Science Center in San Antonio.
Researchers not affiliated with the study called it a good first step but said larger groups from the general population need to be studied over time to verify the stark difference in MCI onset age and the reasons for it. O'Bryant's team looked at two groups of Mexican-Americans in Texas who were taking part in either a community-based or a clinical study of mental aging. Those in the clinical group already were having memory problems.
Studying such groups, which is common in research, limits the ability to draw conclusions to the population at large, said Mary Haan, a biostatistics and epidemiology professor at the University of California, San Francisco, School of Medicine.
Haan has studied cognitive impairment in older Mexican-Americans in Sacramento, California, and found that they have an earlier onset of certain chronic conditions, such as high blood pressure, diabetes and obesity, she said. Those conditions are risk factors for dementia, so "it's reasonable to think they might have an earlier onset" of MCI as well, she said.
O'Bryant's team also saw a similar early onset of diabetes: at an average age of 48 for Mexican-Americans and 57 for non-Hispanics, according to the study. His group suspects that depression, education level and metabolic dysfunction, which can include diabetes, are risk factors for Mexican-Americans who develop cognitive impairment.
Understanding those risks is fertile ground for future research, O'Bryant said, and a key to finding treatments.
"He's at the beginning of a process that could go on for many years," said Dallas Anderson, program director in epidemiology at the National Institute on Aging, part of the National Institutes of Health, which provided some funding for the study. "We need to be like detectives to get to the bottom of it." Scientists are eager to find treatments that can prevent or delay the onset of Alzheimer's. Of the medicines in use today, some may help lessen severity of symptoms, such as memory loss and confusion, but for a limited time, according to the Alzheimer's Association.
More than 5 million Americans have Alzheimer's disease, costing society US$203 billion, the association says. That cost is expected to rise to US$1.2 trillion by 2050.
Hispanics are believed to be 1.5 times more likely than non-Hispanic whites to develop Alzheimer's disease, according to the association, but are often diagnosed later and cared for by their families.
"If you can find a treatment to delay someone from getting the disease by five years, you cut the prevalence of the disease in half because people die of other things, which, in my opinion, is a blessing," O'Bryant said.
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