VANCOUVER, British Columbia » Stress can lead to heart disease, hypertension and diabetes, but people are notoriously unreliable in reporting their own stress levels.

That’s why Dan Brown, an anthropologist and interim vice chancellor for research at the University of Hawaii at Hilo, has been studying the body’s physical and chemical responses to stress. And he has found wide variations among individuals and ethnic groups.

"Stress leads to certain kinds of physiological changes, including increased blood pressure and cardiac output," Brown said Sunday at the annual meeting of the American Association for the Advancement of Science. "It increases your inflammation. And it mobilizes these energy reserves, and over a prolonged period may increase risk for various nasty outcomes."

Stress is not always bad, he emphasized.

"If the bear is chasing you, it is pretty good to have a stress response, where your heart is beating fast and your blood pressure is up and you’re breathing deeply and you’re throwing a lot of glucose into your bloodstream and it all goes to your muscles and it’s a fight-or-flight response," he said. "That’s an adaptive thing."

Also, one person’s stress trigger can be another’s salve.

"They put you on hold on a phone and play you elevator music," said Brown. "And that is supposed to relax people, but I hate elevator music and it makes me very stressed. So a stimulus is perceived differently by different people based on your knowledge of what can be a threat and based on your knowledge of how you can cope with things."

Asking someone whether they feel stress often results in "reporting biases," he said.

In a study of Hawaii nurses, for instance, Brown found that Filipino-American women were more likely to report anxiety than were their European-American counterparts when doing household chores on top of their regular jobs.

"These are all nurses working in the same hospitals," he said. "When I looked at blood pressure, though, it was European-American women who had elevated blood pressure. So they are reacting differently than what they are reporting."

Other so-called "biomarkers" for stress include heart rate and the urine levels of epinephrine (adrenaline) and other so-called catecholamines, hormones produced by the adrenal glands, including dopamine and norepinephrine. Other markers are pulse, levels of the hormone cortisol, and galvanic skin response — palms conduct electricity better when they’re sweaty.

In his study of Filipino nurses, Brown also divided them into two groups by ancestral language, Ilocano and Visayan, which is spoken on Cebu.

"These were Filipino-Americans, mostly immigrants. Some were second-generation. And they came from two areas of the Philippines that are actually culturally quite distinct," he said. "What I found was that there were real strong differences between the ethnic groups in their reporting of stress. But when you looked at the catecholamine levels, there is no difference. So what we saw was a cultural difference in how you reported stress."

As part of his research, Brown fitted volunteers with machines that recorded blood pressure every 15 minutes or so as they went through their daily tasks. In conjunction, the test subjects also kept a journal on where they were and what they were doing at various times — working, exercising, sitting, standing or reclining — and what mood they were in: angry, anxious, calm or happy.

The blood pressure levels have proved to parallel the reported emotional states fairly well, said Brown.

"Blood pressure is constantly changing, and if it didn’t you’d be in trouble," he said. "If you started walking up a flight of stairs and your blood pressure didn’t go up, you probably wouldn’t make it to the top. So blood pressure is a state, not a trait, in psychological parlance."

The blood pressure studies were able to pinpoint specific events that triggered stress reactions.

In Brown’s case, one day the most stressful events were the "morning madness" of getting the kids off to school, a meeting with the dean and a meeting with a student whose "dog ate his homework," he recalled.

Brown spoke at the Vancouver Convention Center in a session called "Making Visible the Invisible," dealing not only with measuring stress, but also pain and calories in food.

Dr. Marc Heft, a professor of oral surgery at the University of Florida, reported an experiment in which volunteers were asked to keep their hands in icy water for as long as they could. With no other information, the men kept their hands in the water longer than the women.

But when the test subjects were told that the average male, or female, kept their hands in the water for 30 seconds, or alternatively 90 seconds, not only did both groups keep their hands in the water longer, but the males and females also showed comparable endurance.

"Not only that, but the overall assessment of the amount of pain drops off, suggesting that there are other factors than biology that are telling the story," Heft said.