Alzheimer's, Dementia & Mental Health
Personality May Influence Brain Shrinkage in Aging
Brains
Accumulating research suggests people tend to
become more neurotic and less conscientious in early-stage Alzheimer's
By Tony Fitzpatrick
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Denise Head |
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David Balota |
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Jonathan Jackson |
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April 28, 2010 - Psychologists at Washington
University in St. Louis have found an intriguing possibility that
personality and brain aging during the golden years may be linked.
Studying MRI images of 79 volunteers between the
ages of 44 and 88 - who also had provided personality and demographic
data - the researchers found lower volumes of gray matter in the frontal
and medial temporal brain regions of volunteers who ranked high in
neuroticism traits, compared with higher volumes of gray matter in those
who ranked high in conscientious traits.
“This is a first step in seeing how personality
might affect brain aging,” says
Denise Head, PhD, assistant professor of psychology in Arts &
Sciences at Washington University. “Our data clearly show an association
between personality and brain volume, particularly in brain regions
associated with emotional and social processing. This could be
interpreted that personality may influence the rate of brain aging.”
She notes also that the results could be seen as
“the tail wagging the dog.” That is, it is actually brain changes during
aging that influence personality.
“Right now, we can’t disentangle those two, but we
plan to in the future by conducting ongoing studies of the volunteers
over time to note future structural changes,” Head says.
Head’s graduate student
Jonathan Jackson, first author of a recently published paper on the
research in Neurobiology in Aging, says that he, and co-authors Head and
David A. Balota, PhD, professor of psychology, tested the
hypotheses that aging individuals high in neuroticism would show lower
brain volume, while those high in either conscientiousness or
extroversion would have larger brain volume. The extroversion results
were not clear, but the data validated the other two hypotheses.
“There are lots of nonhuman animal studies that
suggest that chronic stress is associated with deleterious effects on
the brain, and this helped us form the hypothesis that we’d see similar
effects in older adults.” Jackson says.
“We assumed that neuroticism would be negatively
related to structural volume," Jackson says.
"We really focused on the
prefrontal and medial temporal regions because they are the regions
where you see the greatest age changes, and they are also seats of
attention, emotion and memory. We found that more neurotic individuals
had smaller volumes in certain prefrontal and medial temporal parts of
the brain than those who were less neurotic, and the opposite pattern
was found with conscientiousness.”
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The amygdala, which is part of the
medial temporal region and involved in emotion processing, was
larger in conscientious individuals but smaller in neurotic
individuals. |
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The orbitofrontal cortex, which is
part of the prefrontal region and involved in social/emotional
processing, showed similar associations with personality. |
“A unique thing that we’ve done is to reliably
measure personality differences and associate them with age-related
effects on brain structures in healthy middle-aged and older adults”
Head says.
“Specifically, we found that neuroticism was associated with
greater age-related decline in brain volume, whereas conscientiousness
was associated with less age-related decline.”
The researchers were interested in healthy aging
brains because, down the road, the findings might serve as a useful
marker for later diagnosis of dementia.
The volunteers they studied are normal control
participants at Washington University’s
Alzheimer’s Disease Research Center (ADRC), led by John C. Morris,
MD, the Friedman Distinguished Professor of Neurology and director of
the ADRC.
One of the first changes in Alzheimer's disease may
be in personality. There is accumulating research from the ADRC and
other institutions that suggest that people tend to become more neurotic
and less conscientious in early-stage Alzheimer's.
“It might be that changes in personality track onto
those people more likely to develop Alzheimer's,” Jackson says.
“It’s
why we looked at older healthy adults because it’s important to track
these relationships in healthy populations before you look at
pathological ones.
"We know that there are degenerative processes
going on before the diagnosis of Alzheimer's. We want to be able to see
if the subtle personality changes might be particular to an early
clinical picture and possibly see if one can predict who will become
demented based on personality changes,” Jackson says.
Another way of looking at the findings, Head says,
is that neuroticism might add an increasing vulnerability to the
pathological processes that go on in aging, particularly in Alzheimer's.
“We will continue to pursue the relationship
between personality and brain structure as one of the earlier processes
in Alzheimer's and hence a possible risk factor,” Head says.
