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."
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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.