People who suffer from depression not only endure the well-known symptoms of hopelessness and despair but also run a heightened risk of developing a heart attack, according to a Johns Hopkins study released yesterday.
Researchers who followed 2,000 residents of East Baltimore for more than a decade found that those with histories of clinical depression had a 4 1/2 times greater chance of having a heart attack than did those with no such history.
"For people who are depressed, this is all the more reason to get treated," said Dr. William Eaton, a professor of mental hygiene at the Johns Hopkins School of Hygiene and Public Health. "Depression is miserable enough -- potentially, the treatment for depression could lower the risk of heart attack."
Researchers were careful to identify people who struggled with depression and only later experienced a heart attack. In this way, Eaton said, they were careful not to confuse this pattern with a widely recognized occurrence -- the sadness that can strike once-vital people who are suddenly sidelined by a heart attack.
"We got the order straight," Eaton said. "It can't be that people were sad because they had a heart attack. They had the depression first."
The findings are reported in this month's edition of the journal Circulation. Its lead author is Laura Pratt, a Hopkins epidemiologist.
Although Eaton could only speculate on how depression could cause heart disease, he said the study all but ruled out anti-depressant medications.
In fact, the incidence of heart attack among people who were taking certain drugs that are known to carry cardiovascular side effects was lower than it was among the larger group of depressed people.
In the project, called the Baltimore Health and Mental Health Study, researchers interviewed approximately 2,000 adults in 1981 and again in 1994. The subjects included adults of all ages, male and female, black and white.
To analyze the connection between depression and heart attacks, researchers concentrated on 1,551 people who had no symptoms of heart disease when the first interviews were done.
Of these, they found 73 people who had histories of depression, and 8.2 percent of them eventually had a heart attack. The heart attack rate was much lower -- 3.3 percent -- among the people who had never struggled with depression.
Eaton said the contrast widened when his team applied statistical methods that ruled out independent risk factors for heart attack. These included smoking and hypertension. When this was done, depressed people were shown to have more than a fourfold risk of heart attack.
People who had suffered prolonged periods of sadness that fell short of depression had twice the heart-attack rate as those without a mood disorder.
In any six-month period, an estimated 9.4 million people in the United States suffer from clinical depression, a condition marked by feelings of hopelessness and profound sadness that often produces thoughts of suicide, according to the American Psychiatric Association.
The study produced a separate finding published in October: depressed people are 2 1/2 times more likely to develop diabetes than are people without depression. Eaton said that finding was "on the border of statistical significance," but considered the heart-attack finding "robust."
The study was funded by the National Institute of Mental Health. Eaton said it was an example of how ordinary citizens, collaborating with research scientists, can produce results that can ultimately benefit public health.
"We could not have done this if people in East Baltimore had not opened their doors and their hearts for the purpose of collaborating with us," he said.
Dr. Robert Carney, a professor of medical psychology at Washington University in St. Louis, said that he and others around the country have been studying this issue for more than a decade. While previous studies suggested a link, he said most have been too small or had some flaw that made the conclusions suspect.
"This certainly is a very excellent study, methodologically," Carney said. "It shows a very strong link."
But Dr. Rita Redberg, assistant professor of medicine and anesthesia at the University of California-San Francisco, said the study would have been stronger if the heart attacks hadn't been self-reported.
"Some people think that any pain in their chest is a heart attack, and people who are more depressed are also more likely to have pains in their chest," said Redberg, who also chairs the American Heart Association's Committee on Women and Cardiology.
Nonetheless, she said she believes the data and noted that it parallels findings on stress and heart attacks. In that case, it's not so much the condition -- but how a person copes with it -- that makes stress a risk factor. It is possible, she said, that depressed people have less effective coping mechanisms than people whose mental health is good.