Neural origins of hot flashes in menopause identified

Scientists, including one of Indian-origin, have found that origins of hot flashes may lie in specific brain regions in menopausal women.
The study, by Wayne State University School of Medicine in US, can inform and eventually lead to new treatments for those who experience the sudden but temporary episodes of body warmth, flushing and sweating.
"The idea of understanding brain responses during thermoregulatory events has spawned many studies where thermal stimuli were applied to the skin. But hot flashes are unique because they are internally generated and studying them presents unique challenges," said Professor Robert Freedman, the study's principal investigator.

"Menopause and hot flashes that result during it are a significant women's health issue of widespread general interest," said co-researcher Vaibhav Diwadkar.
"However, understanding of the neural origins of hot flashes has remained poor. The question has rarely been assessed with in vivo functional neuroimaging.
"In part, this paucity of studies reflects the technical limitations of objectively identifying hot flashes while symptomatic women are being scanned with MRI. Nothing like this has been published because this is a very difficult study to do," he said.

During the course of a single year, 20 healthy symptomatic postmenopausal women ages 47 to 58 who reported six or more hot flashes a day were scanned at the School of Medicine's Vaitkevicius Imaging Center located in Harper University Hospital in Detroit.

The researchers collected skin conductance levels to identify the onset of flashes while the women were being scanned.
Changes in levels allowed researchers to identify a hot flash onset and analyse the concurrently acquired fMRI data to investigate the neural precedents and correlates of the event.
The researchers focused on regions like the brain stem because its sub regions, such as the medullary and dorsal raphe, are implicated in thermal regulation, while forebrain regions, such as the insula, have been implicated in the personal perception of how someone feels.
They showed that activity in some brain areas, such as the brain stem, begins to rise before the onset of the hot flash.

"Frankly, evidence of fMRI-measured rise in the activity of the brain stem even before women experience a hot flash is a stunning result," Diwadkar said.
"When this finding is considered along with the fact that activity in the insula only rises after the experience of the hot flash, we gain some insight on the complexity of brain mechanisms that mediate basic regulatory functions," he said.
These results point to the plausible origins of hot flashes in specific brain regions. The researchers believe it is the first such demonstration in academic literature.
The study was published in journal Cerebral Cortex.