|Study Finds Improved Cognitive Health among Older Americans
Rates of cognitive impairment among older Americans are on the
decline, according to a new study supported by the National Institutes
of Health (NIH) comparing the cognitive health of older people
in 1993 and 2002. Higher levels of education were associated with
better cognitive health.
Researchers said the findings will need to be explored further
to see if they can be observed in other studies and to pinpoint
factors influencing cognition, or the ability to think, learn,
and remember. "These data suggest that we may be experiencing
a shift in the cognitive health of older Americans," said
Richard J. Hodes, M.D., director of the NIA. "Continuing to
track trends will be critically important both for chronicling
changes in brain health and for achieving a better understanding
of factors that may play a role."
The report appears in Feb. 20, 2008, issue of Alzheimer's & Dementia
(now online). The National Institute on Aging (NIA), part of the
National Institutes of Health (NIH), and Harvard University, funded
the study conducted by Kenneth M. Langa, M.D., Ph.D., and colleagues
at the University of Michigan, University of Pennsylvania, and
Group Health Cooperative of Puget Sound in Seattle. The National
Institute of Mental Health (NIMH), also part of NIH, provided additional
The data come from the NIA-supported Health and Retirement Study
(HRS), a national, longitudinal examination of health, retirement
and economic conditions of more than 20,000 men and women over
50. Researchers tested memory and judgment of a large subset of
HRS participants to determine cognitive status in two groups of
people, those age 70 and older in 1993 and in 2002. The scientists
then followed each group for two years to track death rates. They
also looked at levels of education, income, and other factors in
each group, finding that the 2002 participants were wealthier and
had significantly higher levels of education, with 17 percent college-educated
compared to 13 percent in 1993.
The analysis found:
- Cognitive impairment dropped from 12.2 percent in
1993 to 8.7 percent in 2002 among people 70 and older.
- Cognitive impairment was associated with a significantly
higher risk of death in both cohorts.
- Education and financial status appeared overall to
protect against developing cognitive impairment.
- Once older people with higher levels of education
reached a threshold of moderate to severe cognitive impairment,
they had an increased risk of death over the next 2 years compared
to those with lower levels of education.
"Although the trend of improving cognitive health is consistent
with chronic disability reductions since 1984 in those aged 65
and older, replication in other studies is essential," said
Richard Suzman, Ph.D., director of NIA's Social and Behavioral
Research Program, which oversees the HRS. "I'd like
to see further analysis of how education, exercise, medications,
cardiovascular health and lifestyle affect cognitive functioning."
The researchers suspect that improved treatment for stroke, heart
disease, and vascular conditions from 1993 to 2002 might have been
factors in the improvement. Further, they suggested, the results
support the notion of cognitive reserve, which hypothesizes that
the brains of more educated people may be better able to sustain
greater damage from Alzheimer's disease or other pathology
before clinical signs of impairment appear. In the study, the rate
of cognitive impairment among people with higher levels of education
was reduced, for both cohorts. The higher level of education, on
average, in the 2002 cohort may be one important factor in the
lower rate of cognitive impairment in 2002 compared to 1993.
The NIA leads the federal government effort conducting and supporting
research on the biomedical and social and behavioral aspects of
aging and the problems of older people, including Alzheimer's disease
and age-related cognitive decline. For information on dementia
and aging, please visit the NIA's Alzheimer's Disease Education
and Referral (ADEAR) Center at www.nia.nih.gov/alzheimers, or call
1-800-438-4380. For more general information on research and aging,
go to www.nia.nih.gov.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.