Neuroscientists at the Wayne State University School of Medicine have provided the first novel insights into the neural origins of hot flashes in menopausal women in years.
The study may 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, so studying them presents unique challenges," Robert Freedman, the study's principal investigator, 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 Detroit's Harper University Hospital.
The researchers collected skin conductance levels to identify the onset of flashes while the women were being scanned. Skin conductance is an electrical measure of sweating. The women were connected to a simple circuit passing a very small current across their chests.
Changes in levels allowed researchers to identify a hot flash onset and analyze 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 actual 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. 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," study collaborator, Vaibhav Diwadkar, Ph.D., associate professor of psychiatry and behavioral neurosciences, 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 is published in Cerebral Cortex, an Oxford University Press journal.