The latest evidence comes from a new study of siblings in Sweden. Researchers identified about 137,000 people who had been diagnosed with stress-related disorders; the diagnoses included post-traumatic stress disorder or acute stress following a traumatic event, such as the death of a loved one or a violent episode. Then, the researchers identified about 171,000 of their brothers and sisters who had similar upbringings and genes — but no anxiety disorder.
Next, they compared the siblings' rates of cardiovascular disease, including heart attacks, cardiac arrest and blood clots, over a number of years.
The Swedes who had a stress disorder, it turns out, had significantly higher rates of heart problems compared to their siblings.
"We saw [about] a 60 percent increased risk of having any cardiovascular events" within the first year after being diagnosed, says researcher Unnur A Valdimarsdóttir of the Karolinska Institute, a professor of epidemiology at the University of Iceland. Over the longer term, the increased risk was about 30 percent, Valdimarsdóttir says.
The findings, published in the current issue of the medical journal BMJ, "are quite consistent with other studies," says Simon Bacon of Concordia University, who studies the impact of lifestyle on chronic diseases. He points to other studies that show depression, anxiety and stress increase the risk of cardiovascular events. He wrote an editorial that is published alongside the study.
So, when is stress just a normal part of life — something we all just need to deal with — and when does it become so problematic that it sets the stage for disease? Part of the answer depends on how we respond to stress, the scientists say, and on our own internal perceptions about how much stress we're feeling.
We've all experienced the fight-or-flight stress response.
"Imagine you're walking down the street and someone jumps out and gives you a scare," says Bacon. What happens? Your heart rate increases and your blood pressure climbs. "You have that immediate activation," Bacon says. In the short term, this temporary response is good. It gives you what you need to flee or take action.
The problem comes if you start to experience these stress response "activations" even when there's not an imminent threat.
"When people have stress disorders, these systems are being activated at all the wrong times," Bacon says. For instance, with PTSD, "you can get very exaggerated stress responses just thinking about something that happened."
People who experience chronic stress seem to be at highest risk of health problems.
"Over the long term, repeated, persistent [stress] responses will activate the immune system and contribute to inflammation," says Dr. Ernesto Schiffrin, a physician and professor of medicine at McGill University. He says inflammation can set the stage for atherosclerosis, also known as hardening of the arteries. Arteries are the blood vessels that carry blood to your heart and body. When the arteries narrow, this limits blood flow — increasing the likelihood of a heart attack, stroke or other cardiovascular event.
Since we can't wave a magic wand and make stress disappear, what are the best coping options? There's no magic bullet, but day-to-day habits can help tamp down stress.
Schiffrin says he gives his patients this advice: Eat in a healthy way, attempt to have good relationships, have a good attitude, spend time in nature, and exercise. "I think exercise is critical," Schiffrin says.
Let's take a closer look at each of these.
"You don't want to put yourself in a position where you could make your health worse by not doing anything," Bacon says.