Unique Duke Study to Probe how Genetics and Environment Influence Responses to Stress
DURHAM, N.C. -- Being the main caregiver for a spouse
suffering from Alzheimer's disease can be a physically and
emotionally draining experience -- the slow, unrelenting
progression of the disease and its certain outcome put
caregivers under constant pressure that can impact all aspects
of their lives.
How these caregivers respond physically and emotionally to
these demands can vary widely among individuals; some seem able
to cope with the pressure while others suffer physically and/or
A group of Duke University Medical Center researchers
believes that by carefully studying these caregivers they will
be able to unravel the mysteries of why some people can
successfully handle life's stresses in general and why others
fare poorly. The researchers hope to be able to tease apart the
interplay between genetics, neighborhood environment,
psychological makeup and other factors with the ultimate goal
of identifying those most at risk of succumbing to these
stresses so the appropriate interventions can be developed.
Negative responses to stress can include such behavioral
characteristics as anxiety and depression, as well as physical
responses such as cardiovascular disease, hormonal and glucose
imbalances, and high blood pressure.
The novel Duke research project, which begins this month, is
supported by a $2.6 million grant from three agencies of the
National Institutes of Health: the National Institute of
Environmental Health Sciences, the National Institute on Aging
and the National Institute of Mental Health.
During the five-year project, the Duke researchers, led by
Dr. Redford Williams, will conduct in-depth analyses of 200
caregivers of spouses with Alzheimer's disease or similar
dementias. As a control, they will perform the same analyses on
200 people who are similar in all aspects to the caregivers,
but who have a healthy spouse.
"By the end of this study we hope to better understand the
underlying biological and behavioral mechanisms whereby
stressful situations -- like caring for a spouse with
Alzheimer's disease -- can contribute to health disparities
between socioeconomic groups, as well as between racial
groups," said Williams, who is director of Duke's Behavioral
Medicine Research Center. "This is a truly innovative approach
to a complex problem.
"The possible payoff is that we might be able to identify
groups of people with certain characteristics -- whether
psychological, genetic or environmental -- who are at a much
higher risk of developing health problems under stressful
situations and help them through early intervention," Williams
said. "This is truly a study aimed at determining how the
environment and genetics interact in contributing to the
To better understand how the roles of environment and
genetics can impact responses to stress, the researchers chose
caregivers of Alzheimer's disease patients because there is a
well-described body of scientific literature that shows that
these caregivers do suffer from a broad range of physical and
"What makes Alzheimer's disease different from other
diseases is that you gradually lose the person you love, and
while they still have lucid moments, you have to make important
decisions about that person without his or her understanding or
input," said Lisa Gwyther, director of the Family Support
Program (FSP) at the Duke Center for the Study of Aging and
Human Development and co-investigator for the study.
"Many people have this romanticized vision that taking care
of a sick family member comes easily and naturally," Gwyther
continued. "But it doesn't come that easily for everyone, and
it is not what people expect. Most of the stresses experienced
by caregivers come from dealing with the unexpected, which is a
hallmark of the disease."
In addition to documenting the stresses involved in the
actual caregiving, the researchers also plan to conduct a
detailed analysis of the environmental stressors present in
each caregiver's neighborhood.
"We will be using a unique survey developed by our
colleagues at the University of North Carolina at Chapel Hill,
which not only takes into account census data for the
neighborhood, but such factors as the overall quality of the
housing, noise levels, safety issues and the social support
network within the neighborhood," Williams explained.
With this knowledge, the team wants to see how certain
moderators, such as genetics and certain personality traits,
play into a caregiver's response to stress. One truly unique
part of the study, according to Williams, will be elucidating
the role of genetics.
For each caregiver, the team will be looking for a
particular naturally occurring form of a gene that controls the
effects of a neurotransmitter called serotonin on the central
nervous system. Previous studies have demonstrated that low
levels of serotonin have been implicated in such negative
behaviors or traits as hostility, depression, anxiety, alcohol
abuse and smoking.
By the end of this project, we should able to pinpoint how
this different form of the gene influences the responses to
stress in different races as well as by gender," Williams said.
"As results become clear during the study, we plan to share
this information with the community to help improve the
conditions of family members and caregivers who are under a
tremendous amount of stress."
This community outreach will be overseen by the Duke FSP,
which has a long history of providing assistance for families
and professionals caring for patients with Alzheimer's disease
and other similar disorders.