For more than 70% of women, this feeling becomes a regular occurrence during one particular time of their lives: menopause, when their periods stop and they are no longer able to bear children. Yet despite its commonality, very little is known about why hot flashes occur and why some women are more likely to experience them than others.
But a new study, published Wednesday in the journal Menopause
, has found that these moments of heat may come down to a woman's genes.
"We didn't understand the underlying cause," said Carolyn Crandall, professor of medicine at the David Geffen School of Medicine at the University of California, Los Angeles, who led the study. "(But) I suspected there to be a contributing factor from our genes."
To end her suspicion and provide answers, Crandall and her team scanned the entire genomes of more than 17,000 women who participated in the US government's Women's Health Initiative
, during which they provided samples of their DNA and information on their experiences with hot flashes and night sweats.
The UCLA team was looking for particular variations in the women's genes known as single-nucleotide polymorphisms (SNPs) and examined more than 11 million of these SNPs to identify any links with the likelihood of hot flashes.
"This is the first study ever that's looked across the whole genome for changes relating to hot flashes," Crandall said.
Fourteen of the variants identified, located in a specific region of chromosome 4, were linked to women experiencing these types of flashes. "They were all located in a similar area," she said.
This region of DNA encodes a brain receptor called tachykinin receptor 3, which links to the release of the hormone estrogen in the body. Estrogen levels fall when a women experiences menopause, causing her to be less tolerant of temperature changes within her body, so it would make sense that changes in this receptor were associated with whether women experience hot flashes.
"We know estrogen has a role in making a woman less sensitive to temperature changes," said JoAnn Manson, chief of the division of preventive medicine at Brigham and Women's Hospital, who was also involved in the study. "There may be something among women with these variants that influences estrogen receptors ... and what's exciting is that this is consistent with what we know about the biology of menopause."
Interestingly, there was consistency in these gene variants across all ethnicities included in the study: African-American, Hispanic and European descent. Hot flashes are thought to be more common among African-American women, but no difference in the variants was observed.
"The associations were consistent across ethnicities," Crandall said. "There was no significant variation."
Potential for a new treatment
The researchers acknowledge, however, that they cannot account for the role the environment may play in determining which women experience these symptoms of menopause.
They also note that more work now needs to be done by means of replicating the study in another sample of women as well as zooming in on this region of chromosome 4 to further investigate the genetic changes and how they could be influencing the onset of hot flashes.
"These are potentially exciting results ... as these types of genetic findings are hard to come by," said Susan Johnson, professor of obstetrics & gynecology and epidemiology at the University of Iowa, who was not involved in the study. "Although there are not immediate benefits to women with hot flashes from this discovery, it means that we may be coming closer to finding out at least one important reason that women get them."
If these much-anticipated secrets are revealed, the researchers believe they may be able to develop treatments to help women cool these flashes when they occur or even prevent them altogether.
"It may have therapeutic options if we can understand the role of this (genetic) pathway," Crandall said.
Manson agreed: "This (receptor) may in the future may become a drug target for treatments."
The current treatment for women experiencing severe flashes and sweats is estrogen therapy, which aims to increase their tolerance of temperature changes. But this comes with risks, mainly in older women going through menopause, as excess levels of the hormone have been associated with an increased risk of blood clots, stroke and breast cancer.
"Right now, for youngish women ages 55 or 50, estrogen is generally a very effective treatment, (but) as you get older, beyond 60, the risk starts to go up," Johnson said. "This new information gives scientists a clue as to what might someday be a safe, effective way to treat hot flashes for some women."
Safety and a reduced risk are the crucial points when developing new forms of treatment.
"A treatment free of risk would be a tremendous advance in women's health," Manson said. "We don't know if this (research) will yield therapies, but it's a promising start."