Age-Related Smelling Loss Significantly Worse in
Long known that men begin to lose sense of smell
years sooner than women, but this is first study to point to racial or
June 13, 2013 - The ability to distinguish between
odors declines steadily with age, but a new study shows that
African-Americans have a much greater decrease in their sense of smell
than Caucasians. This can have serious consequences. Olfactory loss
often leads to impaired nutrition. It also may be an early warning sign
of neurodegenerative diseases, such as Alzheimer's or Parkinson's, and
can predict death.
The study, published early online in the Journal
of Gerontology: Medical Sciences, found that as they aged,
African-Americans and Hispanics had comparable deficits.
For Hispanics, many of whom are recent immigrants,
social and cultural factors, such as disparities in education and
household assets and health-related cognitive problems, accounted for
the sensory loss.
For African-Americans, however, premature
presbyosmia - age-related declines in the ability to smell - could not
be explained by social, environmental or medical factors.
"We have long known that men begin to lose their
sense of smell some years sooner than women, but this is the first study
to point to racial or ethnic differences," said study author Jayant
Pinto, MD, associate professor of surgery at the University of Chicago.
"What surprised us was the magnitude of the difference. The racial
disparity was almost twice as large as the well-documented difference
between men and women."
Although many people live long lives with only
minor age-related declines in the ability to smell, about 24 percent of
Americans 55 years or older have a measurable problem with their sense
of smell, according to data from the National Institute on Aging. That
rises to about 30 percent for those ages 70 to 80, and to more than 60
percent for those over age 80.
This study was one component of the University of
Chicago-based National Social Life, Health and Aging Project (NSHAP),
the first in-home study of social relationships and health in a large,
nationally representative sample of older adults, ages 57 to 85.
For this project, conducted from 2005 to 2006,
survey teams from the National Opinion Research Center used a standard,
well-validated test to assess the ability of 3,005 older participants to
identify five common odors. The scents were presented one at a time.
Subjects were asked to identify each smell from a set of four choices.
The odors, in order of increasing difficulty, included peppermint, fish,
orange, rose and leather.
Personal information about race and ethnicity was
provided by the study subjects. The surveyors also assessed their
physical and mental health, social and financial resources, education,
and alcohol or substance abuse through questionnaires and careful
The researchers found that:
Only half (49 percent) of those tested
correctly identified five out of five odors; 78 percent got four or
more right, 92 percent got at least three and 97 percent got two or
Performance declined steadily across the age
groups; 64 percent of those age 57 identified all five, but that
fell to 25 percent of those age 85.
Non-white subjects had consistently poorer
performance, scoring 47 percent lower, equivalent to a nine-year
increase in age.
The study confirmed previous reports that women
perform better at this task, equivalent to being five years younger.
This study extended that finding across the age range, 57-85.
Caucasian women typically begin to experience some
loss of smelling acuity in their early 70s, Pinto said. Caucasian men
start about five years earlier, in their late-60s. Black and Hispanic
women start in their mid-60s. Non-white men start in their late-50s or
early 60s. Because the changes occur gradually over several years, many
older people do not notice the decline.
The cause of this disparity is not clear. Genetic
variation may play a role, as could exposure to nerve-damaging
substances in the environment, or both. "Race likely serves as a proxy
for differential environmental exposures and life experiences, which may
interact with biological differences," the authors note.
Certain medications, chronic or recurrent nasal
disease or exposure to various volatile chemicals can harm olfactory
function. "Sanitation workers, for example, are often affected," Pinto
said. "They are routinely exposed to noxious odors that can trigger
Presbyosmia can have a substantial impact on
wellbeing, the researchers emphasize. Those who can't detect odors are
unable to maintain their personal hygiene. Food smells have a huge
impact on how foods taste, so many with smelling deficits lose the joy
"They make poor food choices, get less nutrition,"
Pinto said. "They can't tell when foods have spoiled or detect odors
that signal danger, like a gas leak or smoke."
Follow-up interviews with the original study
subjects five years later confirmed earlier findings that impaired
olfaction also is a harbinger of mortality. Those with the poorest sense
of smell in 2006 were three times more likely to have died by 2011 than
those with normal smell function.
"Olfaction is the canary in the coal mine of human
health," Pinto said.
The National Institutes of Health—including the
National Institute on Aging, the Office of Women's Health Research, the
Office of AIDS Research, the Office of Behavioral and Social Sciences
Research—and the McHugh Otolaryngology Research Fund, the American
Geriatrics Society, and the Institute of Translational Medicine at the
University of Chicago funded the study. Additional authors were Philip
Schumm, Kristen E. Wroblewski, David W. Kern and Martha K. McClintock,
from the University of Chicago. Linda Waite is the principal
investigator of NSHAP.
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