Alzheimer's doctors are increasingly concerned about Hispanic patients, and not just because they make up the country's largest, fastest-growing minority.
Studies suggest that many Hispanics may have more risk factors for developing dementia than other groups, and a significant number appear to be getting Alzheimer's earlier.
Also, surveys indicate that Latinos, less likely to see doctors because of financial and language barriers, more often mistake dementia symptoms for normal aging, delaying diagnosis.
"This is the tip of the iceberg of a huge public health challenge," said Yanira Cruz, president of the National Hispanic Council on Aging. "We really need to do more research in this population to really understand why is it that we're developing these conditions much earlier."
It is not that Hispanics are more genetically predisposed to Alzheimer's, say experts, who say the diversity of ethnicities that make up Hispanics or Latinos make a genetic explanation unlikely. Rather, experts say several factors, many linked to low income or cultural dislocation, may put Hispanics at greater risk for dementia, including higher rates of diabetes, obesity, cardiovascular disease, stroke and possibly hypertension.
Less education may make Hispanic immigrants more vulnerable to those medical conditions and to dementia itself, because, scientists say, education may increase the brain's plasticity or ability to compensate for symptoms. And some researchers cite as risk factors stress from financial hardship or cultural adjustment.
The Alzheimer's Association says that about 200,000 Latinos in the United States have Alzheimer's, but that by 2050, based on Census Bureau figures and a study of Alzheimer's prevalence, the number could reach 1.3-million. (It predicts that the general population of Alzheimer's patients will grow to 16-million in the same period, from 5-million now.)
"We are concerned that the Latino population may have the highest amount of risk factors and prevalence, in comparison to the other cultures," said Maria Carrillo, the association's director of medical and scientific relations.
Scientists are searching for what sets Latinos apart. "There's no gene at this point that we can say this is just for Latinos," said Dr. Rafael Lantigua, a professor of clinical medicine at Columbia University Medical School.
Dr. Steven Arnold, director of the Penn Memory Center at the University of Pennsylvania, studied 2,000 white, African-American and Latino Alzheimer's patients.
Arnold found that the Latinos, mostly low-income, poorly educated Puerto Ricans, many with diabetes, "have more depression," and their scores on tests in Spanish measuring dementia averaged about 15 percent lower than African-Americans and about 30 percent lower than non-Hispanic whites. Latinos were on average about three-and-a-half years younger than non-Hispanic whites and about five years younger than African-Americans, he said.
Mary N. Haan, a University of Michigan epidemiologist heading the Sacramento Area Latino Study on Aging, studied 1,800 Mexican-Americans over 10 years and found greater likelihood of Alzheimer's for those more "acculturated" to American society, based on a number of factors, including diet and social networks. Haan attributed that to higher stress from being "relatively poorer off" and "more socially isolated."