Men and women have different reactions from the region of the brain that manages stress, heart rate and blood pressure when presented with certain stimuli.

Researchers from the UCLA School of Nursing have discovered that cardiovascular diseases may manifest differently in the two sexes, which could lead to men and women being diagnosed and treated differently for the same disease.

According to the study, the anterior insula part of the brain plays a greater role in cardiovascular regulation than posterior areas during a predominantly parasympathetic withdrawal challenge, with opposite lateralization between the two sexes.

“In females, the left anterior-most gyrus responded distinctly from other regions than males,” the study states. “Those sex-specific structural and functional brain patterns may contribute over time to variations in cardiovascular disease between the sexes.”

The researchers gave functional MRI scans to volunteers to measure brain activity by detecting changes in the blood flow of volunteers performing hand-grip exercises to raise both blood pressure and heart rate through signals from the brain.

This revealed that the insular cortex—made up of gyri or folds—responded differently in activity between men and women. The right side of the front insular gyrus was activated by the hand grip exercise in women more than men, who had a greater left-side activation of the same region.

Women also showed a higher resting heart rate than men but had a smaller heart rate increase when challenged with the hand-grip exercise.

The new study builds on previous research that saw volunteers use the Valsalva maneuver—a maneuver performed by attempting to exhale against a closed airway by having participants close their mouths and pinch their noses shut while pressing out.

This maneuver led to changes in blood pressure.

“With the hand grip, the differences were in the left side of the brain, while in the Valsalva study, the differences appeared on the right side, which was a surprise at first,” Paul Macey, associate professor of nursing at UCLA, said in a statement. “What both studies show, however, is that healthy men's and women's brains respond differently, so we may have to re-evaluate separately in men and women what constitutes a disease state versus a healthy state to see if people are more or less vulnerable to cardiovascular illness according to their sex.”

The study also examined the middle area of the brain called the insular gyri, which has been challenging to test until recent advancements in imaging techniques.

Macey said his team will attempt to map the functions of this area to make connections between changes and the risks of a wide range of diseases.

The study was published in the Biology of Sex Differences