July 10 (HealthDay News) -- Anger and other forms of mental stress cause dilation of the neck's carotid arteries and a rush of blood to the brain in healthy people, but this doesn't occur in those with high blood pressure.

That's the finding of U.S. researchers who used ultrasound imaging to monitor the carotid arteries and an artery in the brains of 58 volunteers while they performed tasks designed to provoke mental stress, including math, reading and anger recall tests.

The participants included 30 healthy people and 28 with high blood pressure. In the healthy volunteers, mental stress caused dilation of the carotid arteries and increased blood flow to the brain. This response wasn't seen in those with high blood pressure.

The absence of the required increase in blood flow to the brain during mental activities could affect cognition and cerebral activity during the performance of complex brain tasks, said the researchers from the University of Southern California and Cedars-Sinai Medical Center, both in Los Angeles.

"Inappropriate vasoconstriction, or lack of dilation in response to mental stress in stable coronary heart disease, contributes to the genesis of myocardial ischemia and confers an increased risk in patients with coronary artery disease," researcher Tasneem Naqvi said in a news release. "It will be interesting to see whether the lack of mental stress-induced dilation we found defines subjects at increased risk of future cerebral events."

The study was published online July 3 in the journal Cardiovascular Ultrasound.

SOURCE: BioMed Central, news release, July 2009