Older Adults With Depressive Symptoms Are More Likely To Become Cognitively Impaired
March 8, 2006
Older adults with depressive symptoms are more likely than those without
depression to develop mild cognitive impairment (MCI) within six years,
according to a study conducted by researchers at the San Francisco VA Medical
Center and the University of California, San Francisco.
The greater the degree of depression, the more likely the impairment, the
researchers found.
"This is important, because mild cognitive impairment often precedes
dementia," notes lead author Deborah Barnes, PhD, MPH, a mental health
researcher at SFVAMC. Approximately 50 percent of patients diagnosed with MCI go
on to develop dementia within three years, according to the study authors.
The study also found no correlation between depression and vascular disease
a significant finding, say the authors, because other researchers have
hypothesized that vascular disease might lead to both depression and cognitive
impairment by causing inadequate blood flow to different brain structures.
"We found no evidence to support that hypothesis," reports Barnes, who
is also an assistant professor of psychiatry at UCSF.
The study appears in the March, 2006 issue of Archives of General Psychiatry.
The researchers looked at 2,220 participants in the Cardiovascular Health Study,
a longitudinal prospective study of adults 65 and older living in four American
communities that is sponsored by the National Heart, Lung, and Blood Institute.
The researchers measured the subjects' depressive symptoms using a standard
depression scale. Six years later, the subjects were assessed for MCI by a team
of dementia experts.
Ten percent of subjects with no depressive symptoms went on to develop MCI, and
13.3 percent of subjects with low depressive symptoms did. In contrast, 19.7
percent of subjects with moderate to high depression developed MCI after six
years nearly twice the rate of subjects with no depressive symptoms.
The findings were consistent among all subgroups in the study men and
women, younger and older, with and without vascular disease, and regardless of
education level.
One major implication of the study, according to Barnes, is that family members
and health care providers should pay attention when an older person seems newly
depressed. "Even if they don't have cognitive impairment at that time, our
study suggests that you probably want to keep an eye on them," she says.
"Depression might be an early sign of neurodegeneration in fact, it
might be the first symptom that a family member notices."
Kristine Yaffe, MD, chief of geriatric psychiatry at SFVAMC and the principal
investigator of the study, says the next step is to investigate whether treating
older adults with newly diagnosed depressive symptoms might be effective in
preventing the development of MCI. "Perhaps getting a family member in for
early treatment would make a difference," she speculates. "We don't
know the answer yet, but I think it's important to evaluate." Yaffe is also
associate professor of psychiatry, neurology, and epidemiology at UCSF.
Barnes says she would also like to see other researchers investigate the reasons
for the association between depression and MCI. "If vascular disease is not
the mechanism, what is?" she asks. "One theory is that people who are
undergoing stress or experiencing depression often have elevated levels of the
stress hormone cortisol. There is growing evidence that this may lead directly
to brain damage in the hippocampus," a part of the brain that plays a
significant role in memory and Alzheimer's disease. "It would be good to
find out," she concludes.
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Co-authors of the study were George S. Alexopoulos, MD, of Cornell University;
Oscar L. Lopez, MD, of the University of Pittsburgh School of Medicine; and Jeff
D. Williamson, MD, MHS, of Wake Forest University School of Medicine.
The research was supported by grants from the National Heart, Lung, and Blood
Institute, the National Institute on Aging, and the National Alliance for
Research on Schizophrenia and Depression.
UCSF is a leading university that consistently defines health care worldwide by
conducting advanced biomedical research, educating graduate students in the life
sciences, and providing complex patient care.
Contact: Steve Tokar
steve.tokar@ncire.org
University of California - San
Francisco