|by Daniel Pendick
African-Americans appear to develop Alzheimer’s
disease and other forms of dementia
more often than whites. We know this because of studies comparing
the two groups under controlled conditions. Researchers recruit
older adults from both races, who then undergo neuropsychological
tests to measure memory,
reasoning, and other basic mental skills.
Later, people in both groups take the test again. Some still
test normal for their age; others show signs of cognitive
decline or even symptoms of dementia. After following the
groups long enough, researchers can calculate how blacks and
whites may differ in their risk of dementia.
Neuropsychologist Jennifer Manly, Ph.D., is involved in just
such a study with her colleagues at Columbia University: the
Washington Heights-Inwood Columbia Aging Project. Since 1992,
they have followed a group of older New Yorkers in two racially
diverse Manhattan neighborhoods, Washington Heights and Inwood.
It turns out the risk of dementia varies in these neighborhoods
quite a bit depending on the person’s race or ethnic
heritage. Indeed, the African-Americans are 2.3 times more
likely to develop Alzheimer’s Disease than their white
In studying risk for dementia and diagnosing the disease,
it’s critical that the neuropsychological
tests work the same among people from diverse backgrounds.
If not, then the risks may be exaggerated, or underestimated.
Some may be diagnosed inaccurately, or missed altogether.
Manly’s research in Washington Heights and Inwood has
revealed that inequalities in “educational experience”
— the quality of education the people receive, not merely
how many years they spend in classrooms — accounts for
some of the difference in scores between African-Americans
and other groups. And she thinks she’s found a way to
level the testing field: measure the person’s reading
“What we’re finding is that reading level, in
every racial and ethnic group, and at all levels of education,
helps us predict who will experience cognitive decline,”
Manly says. “If we don’t take into account someone’s
reading level, even though we have their years of education,
it doesn’t necessarily reflect their educational experience.”
Tests for diagnosing dementia use total years in school to
estimate a person’s “cognitive reserve.”
Hypothetically, you end up with greater cognitive reserve
by attending more years in school. More educated people, studies
suggest, are at lower risk of Alzheimer’s disease and
show less mental decline with aging.
Education may impart skills and knowledge that allow people
to compensate for declining brain function. Conversely, less-well-educated
people tend to develop dementia sooner and decline faster.
“People with very little formal education are more vulnerable
to the effects of aging and Alzheimer’s pathology on
the brain,” Manly explains.
By asking an elderly person how many years she went to school,
doctors or Alzheimer’s researchers get an idea of how
well the person ought to score on cognitive tests. The less-educated
person’s “high score” may be the same as
a more-educated person’s “low” score. It’s
all relative to education.
Manly’s research suggests years of education does not
level the field between racial and ethnic groups. The reason
may be that African-Americans who were schoolchildren in the
segregated South were not provided the same quality of education
as white children. Black children attended fewer months per
year in schools with lower funding, less teacher training,
and inferior books.
Testing reading skill might level the playing field, Manly
thought, because it reflects formal schooling as well as subsequent
self-taught knowledge. The Washington Heights-Inwood Columbia
Aging Project provided a way to see the effect of reading
level on test scores.
About 1,000 people participated in the reading study. The
participants were given a standard reading test to divide
them into “high literacy” and “low literacy”
groups. The test measures the ability to name letters and
pronounce words out of context. It’s essentially a test
of one’s ability to process written language.
The team returned to retest for changes in cognitive function
every 18 to 24 months. People with low reading levels showed
more memory loss over time than people at a higher reading
level — just what you would expect to see if reading
level reflects cognitive reserve. When reading level is factored
in, the disparity in test scores between black and white people
in Washington Heights narrows. Literacy also predicted mental
decline more strongly than either race or years of education.
“It’s a strong predictor of cognitive decline
across racial groups,” Manly says. “In fact, it’s
stronger than race itself.”
Diversity and dementia
Culturally appropriate tests will allow researchers to accurately
determine differences in risk among groups so prevention efforts
can be targeted properly. It may also be useful on the treatment
side of things. Right now, people from minority groups are
underrepresented in clinical trials of new drugs. Scientists
hope future treatment trials will be more diverse.
But if they get their wish, neuropsychological tests will
have to be carefully designed to reflect the diverse Alzheimer’s
population. That way, the people who suffer from the highest
rates of dementia may get the full benefit of early diagnosis,
despite past inequities in the schoolroom.
Copyright © 2008 Memory Loss and the Brain
Cognitive decline and literacy among ethnically diverse elders,
by Jennifer Manly and others. (Journal of Geriatric Psychology
and Neurology, 2005, Vol. 18. pp. 213-217.)
“Racial differences in the progression of cognitive
decline in Alzheimer disease,” by Lisa L. Barnes and
others. (American Journal of Geriatric Psychology, November
2005, Vol. 13, pp. 1-9.)
“Implementing diagnostic criteria and estimating frequency
of mild cognitive impairment in an urban community,”
by Jennifer J. Manly and others. (Archives of Neurology, November
2005, Vol. 62, pp. 1739-1746.)
“Potential ethnic modifiers in the assessment and treatment
of Alzheimer’s disease: challenges for the future,”
by Warachal E. Faison and others. (International Psychogeriatrics,
2007, Vol. 19, pp. 539-558.)
“Cognitive functioning among African American older
adults,” By Sheila Black. (African American Research
Perspectives, Spring/Summer 2004, Vol. 10, Issue 1, pp. 106-118.)