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Alzheimer's disease poses a special risk to African-Americans. Studies show they're up to twice as likely as white Americans to develop the disease. Now NPR's Jon Hamilton reports scientists have found evidence of a biological difference that might help explain the racial disparity.
JON HAMILTON, BYLINE: Most of what scientists know about Alzheimer's comes from studies of white people. And that's a problem, says John Morris, a researcher at Washington University in St. Louis.
JOHN MORRIS: We know relatively little about whether Alzheimer's disease is manifested in a identical way in underrepresented groups, such as African-Americans or Latino or Asians.
HAMILTON: So Morris and a team of researchers have been reaching out to the African-American community in St. Louis. And that effort led to a study that included 173 black participants as well as more than 1,000 whites. Morris says about a third of all patients were in the early stages of dementia.
MORRIS: So we set out to see if the disease process seems to be the same in both racial groups.
HAMILTON: The study used brain scans and samples of spinal fluid to look at the biological hallmarks of Alzheimer's, amyloid plaques and tangles made up of proteins called tau. Morris says blacks and whites were no different when it came to plaques.
MORRIS: However, the tau proteins were notably different.
HAMILTON: Spinal fluid from African-Americans contained lower levels of tau protein. And yet, these lower levels do not appear to indicate a lower risk of Alzheimer's in a black person the way they do in a white person. Morris says the finding, which appears in the journal JAMA Neurology, could be a big deal.
MORRIS: It implies that the biological mechanisms underlying Alzheimer's disease may be very different in racial groups. And if so, the way we try to diagnose and treat may be race-dependent.
HAMILTON: Morris says a biological difference might also help explain why African-Americans appear more likely to develop Alzheimer's. The study was accompanied by an editorial from Lisa Barnes, a researcher at Rush University in Chicago.
Barnes says she's excited that the research was done at all. However, she says the results need to be confirmed by a study that includes many more African-Americans. And that will be a challenge.
LISA BARNES: When you try to go to populations that have been sort of marginalized and abused by past research, it becomes very, very difficult.
HAMILTON: Barnes says one way to increase the numbers is for research centers to work together on studies.
BARNES: If we start to pool our numbers together, we'll be able to do more than just one center alone.
HAMILTON: And Barnes says researchers will also have to reach out to groups that have been hesitant to take part in scientific studies.
BARNES: We really need the minority communities to be involved as well and to really, you know, have a voice in what we're finding and to really walk this path with us. You know, we can't do it by ourselves.
HAMILTON: Barnes hopes the new study represents a step toward better collaboration. Jon Hamilton, NPR News.