Register for First Sister Study Results Reinforce the Importance of Healthy Living
U.S. Department of Health and Human Services
NATIONAL INSTITUTES OF HEALTH NIH News National Institute of Environmental
Health Sciences (NIEHS)
http://www.niehs.nih.gov
CONTACT: Robin Mackar, 919-541-0073, e-mail:
rmackar@niehs.nih.gov
Women who maintain a healthy weight and who have lower perceived stress may be
less likely to have chromosome changes associated with aging than obese and
stressed women, according to a pilot study that was part of the Sister Study.
The long-term Sister Study is looking at the environmental and genetic
characteristics of women whose sister had breast cancer to identify factors
associated with developing breast cancer. This early pilot used baseline
questionnaires and samples provided by participants when they joined the Sister
Study.
Two recent papers published in Cancer Epidemiology Biomarkers and Prevention
looked at the length of telomeres, or the repeating DNA sequences that cap the
ends of a person’s chromosomes. Telomere length is one of the many measures
being looked at in the Sister Study. Telomeres protect the ends of chromosomes
and buffer them against the loss of important genes during cell replication.
Over the course of an individual's lifetime, telomeres shorten, gradually
becoming so short that they can trigger cell death. The papers show that factors
such as obesity and perceived stress may shorten telomeres and accelerate the
aging process.
"Together these two studies reinforce the need to start a healthy lifestyle
early and maintain it," said Linda Birnbaum, Ph.D., the director of the National
Institute of Environmental Health Sciences (NIEHS), part of the National
Institutes of Health. The researchers who published these papers are from the
NIEHS which sponsors the Sister Study.
The papers are the first findings coming out of the Sister Study. The Sister
Study is just completing its enrollment of 50,000 women aged 35-74 to
prospectively study risk factors for breast cancer. "We anticipate a wealth of
information to come out of the Sister Study," said Dale Sandler, Ph.D., chief of
the Epidemiology Branch at NIEHS and principal investigator of the Sister Study.
"Not only do we hope to find out more about the environmental and genetic
factors that might lead to breast cancer, we also want to learn more about how
factors such as stress, diet and exercise might impact cancer and other disease
risks."
One of the studies published this week found that women who were obese for a
long time had reduced telomere length. The researchers looked at the
relationship between various measures of current and past body size and telomere
length in 647 women enrolled in the Sister Study. They found that women who had
an overweight or obese body mass index (BMI) before or during their 30s, and
maintained that status since those years, had shorter telomeres than those who
became overweight or obese after their 30s. "This suggests that duration of
obesity may be more important than weight change per se, although other measures
of overweight and obesity were also important," said Sangmi Kim, Ph.D.,
epidemiologist and lead author on the paper. "Our results support the hypothesis
that obesity accelerates the aging process," said Kim.
The other paper published in February looked at the association between telomere
length and the perceived stress levels of 647 women enrolled in the Sister
Study, and found that similar to the obesity finding, stress can also impact
telomere length. The researchers extracted DNA from blood drawn during initial
enrollment to estimate telomere length, and measured levels of stress hormones
in urine samples the women provided. Additionally, the researchers used a
standardized scale to characterize levels of perceived stress based on answers
to questions about how stressful participants perceived their life situations.
In general, the researchers report that women in the Sister Study typically
reported low levels of perceived stress.
"Even so, women who reported above-average stress had somewhat shorter
telomeres, but the difference in telomere length was most striking when we
looked at the relationship between perceived stress and telomere length among
women with the highest levels of stress hormones," said Christine Parks, Ph.D.,
an NIEHS epidemiologist and lead author on the paper. "Among women with both
higher perceived stress and elevated levels of the stress hormone epinephrine,
the difference in telomere length was equivalent to or greater than the effects
of being obese, smoking or 10 years of aging."
The researchers also found that the effects of stress may be stronger in older
women. They found that among women 55 years and older, those with higher
perceived stress had 5 percent shorter telomeres than women with low stress
levels. "More research is needed to determine if the shortening of telomeres in
these women is related to aging or hormonal differences in the stress response,
or simply represents the accumulated effects of stress across the lifespan,"
said Parks.
"These papers remind us that there are things people can do to modify their
behavior and live healthier lives, such as maintain a healthy weight and
cultivate healthy responses to stress," said Birnbaum.
The NIEHS supports research to understand the effects of the environment on
human health and is part of NIH. For more information on environmental health
topics, visit our website at http://www.niehs.nih.gov.
The National Institutes of Health (NIH) — The Nation's Medical Research Agency —
includes 27 Institutes and Centers and is a component of the U.S. Department of
Health and Human Services. It is the primary federal agency for conducting and
supporting basic, clinical and translational medical research, and it
investigates the causes, treatments, and cures for both common and rare
diseases. For more information about NIH and its programs, visit www.nih.gov.
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References:
Kim S, Parks CG, DeRoo LA., Chen, H, Taylor JA, Cawthon RM, Sandler DP. Obesity
and Weight Gain in Adulthood and Telomere Length. Cancer Epidemiology Biomarkers
& Prevention 2009;18(3):816-20 March 2009.
Parks CG, Miller DB, McCanlies EC, Cawthon RM, Andrew ME, DeRoo LA, Sandler, DP.
Telomere Length, Current Perceived Stress, and Urinary Stress Hormones in Women.
Cancer Epidemiology Biomarkers & Prevention 2009; 18(2): 551-560. February 2009.
