Distress-prone people more likely to develop
Alzheimer's disease
Dec. 12, 2003 – People who tend to experience
psychological distress are more likely to develop Alzheimer's disease
than people who are less prone to experience distress, according to a
study published in the December 9 issue of Neurology, the scientific
journal of the American Academy of Neurology.
In the study, those who most often experience
negative emotions like depression and anxiety were twice as likely to
develop Alzheimer's disease as those who were least prone to experience
negative emotions.
The study was part of a larger study of older
Catholic nuns, priests and brothers. In the study, 797 people with an
average age of 75 were evaluated when they started the study and then on
a yearly basis. Participants were evaluated on their level of proneness
to stress with a rating scale that has been proven reliable.
Participants rate their level of agreement (strongly disagree, disagree,
etc.) with statements such as "I am not a worrier," "I often feel tense
and jittery," and "I often get angry at the way people treat me."
"People differ in their tendency to experience
psychological distress, and this is a stable personality trait
throughout adulthood," said study author Robert S. Wilson, PhD, of Rush
University Medical Center in Chicago, Ill. "Since chronic stress has
been associated with changes in the hippocampal area of the brain and
problems with learning and memory, we wanted to test the theory that
psychological distress may affect the risk of developing Alzheimer's
disease."
Wilson said the findings are important because
evidence has shown that many of the adverse effects of stress on the
brain can be blocked by drugs, including antidepressants. "But much more
research is needed before we can determine whether the use of
antidepressants could help reduce the risk of Alzheimer's disease," he
said.
During an average of 4.9 years of follow-up, 140
people in the study developed Alzheimer's disease. Those high in
proneness to stress – in the 90th percentile – were twice as likely to
develop Alzheimer's disease as those in the 10th percentile.
Proneness to stress was related to decline in
episodic memory. Episodic memory is measured by asking participants to
recall a list of words or a story. Problems with episodic memory are
typical in people with Alzheimer's disease. Episodic memory ability
declined 10 times faster in those high in distress proneness than in
those low in distress proneness.
The researchers also evaluated the participants on
their level of symptoms of depression. Because symptoms of depression
are manifestations of psychological distress, the researchers analyzed
the data while controlling for symptoms of depression, but the results
were not changed.
The researchers also measured the participants'
level of cognitive activity by asking them how often they did
cognitively stimulating activities, such as reading a book. To see
whether cognitive activity could account for the relationship between
distress proneness and Alzheimer's, the researchers analyzed the data
while controlling for cognitive activity, but the results were not
changed.
To investigate whether proneness to distress was an
early sign of Alzheimer's disease rather than a risk factor for the
disease, the researchers studied the brains of 141 study participants
who died during the course of the study. Of those, 57 met the criteria
for probable Alzheimer's disease. The researchers found that proneness
to distress was not related to measures of Alzheimer's disease
pathology, such as plaques and tangles in the brain.
"This result suggests that stress proneness is a
co-factor leading to dementia in Alzheimer's disease, but these results
need to be confirmed," said John C.S. Breitner, MD, MPH, of the VA Puget
Sound Health Care System and the University of Washington in Seattle,
who wrote an editorial accompanying the study.
Wilson said that "we are indebted to the
extraordinary efforts of the participants of the Religious Orders Study
who have not only undergone hours of examinations over the years but
have also donated their brains and in so doing have given science a
unique opportunity to advance our understanding of Alzheimer's disease."
Notes:
The study was supported by grants from the National
Institute on Aging.
The American Academy of Neurology, an association
of more than 18,000 neurologists and neuroscience professionals, is
dedicated to improving patient care through education and research. A
neurologist is a doctor with specialized training in diagnosing,
treating and managing disorders of the brain and nervous system such as
stroke, Alzheimer's disease, epilepsy, Parkinson's disease, autism and
multiple sclerosis.
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