Depression is a known risk factor for cardiovascular disease, but as a person's depression improves -- or grows worse -- their risk for heart disease has remained largely unknown.
But now, a new study by researchers at the Intermountain Medical Center Heart Institute in Salt Lake City found that effectively treating depression can reduce a patient's chance of having a stroke, heart failure, a heart attack or death.
In fact, effective treatment for depression can reduce a patient's heart risks to the same level as those who never had short-term depression, the study found.
"Our study shows that prompt, effective treatment of depression appears to improve the risk of poor heart health," said Heidi May, PhD, a cardiovascular epidemiologist with the Intermountain Medical Center Heart Institute.
"With the help of past research, we know depression affects long-term cardiovascular risks, but knowing that alleviating the symptoms of depression reduces a person's risk of heart disease in the short term, too, can help care providers and patients commit more fully to treating the symptoms of depression," she said. "The key conclusion of our study is: If depression isn't treated, the risk of cardiovascular complications increases significantly."
Results of the study will be presented at the 2016 American College of Cardiology Scientific Sessions in Chicago on April 2 at 2:45 p.m., CDT.
Researchers haven't completely understood whether a short-term encounter with depression affects a person's cardiovascular risk forever, or how changes in the symptoms of depression over time affect cardiovascular risk.
Dr. May and her team found answers to these questions by studying data compiled in Intermountain Healthcare's depression registry, a database of more than 100,000 patients.
"There's little publically-available data about this question," Dr. May said. "But now with the help of Intermountain's depression registry, we have the ability to start answering some of these difficult questions."
The Intermountain Medical Center Heart research team compiled information from 7,550 patients who completed at least two depression questionnaires over the course of one to two years.
Patients were categorized based on the results of their survey as never depressed, no longer depressed, remained depressed, or became depressed. Following each patient's completion of the last questionnaire, patients were followed to see if they had any major cardiovascular problems such as a stroke, heart failure, heart attack or death.
At the conclusion of the study, 4.6 percent of patients who were no longer depressed had a similar occurrence of major cardiovascular complications as those who had no depression at all (4.8 percent).
Those who remained depressed, however, and those who became depressed throughout the study, had increased occurrences of major cardiovascular problems -- their rates were 6 and 6.4 percent, respectively. Treatment for depression resulted in a decreased risk of cardiovascular risk that was similar to someone who didn't have depression.
As for the practical application of this study, Dr. May said the research indicates that effective treatment for depression decreases the risk of having cardiovascular problems in the short term, but further study is needed to identify exactly what that treatment should include.
"What we've done thus far is simply observe data that has previously been collected," Dr. May said. "In order to dig deeper, we need do a full clinical trial to fully evaluate what we've observed."
Because of the complex nature of depression, it's hard to say whether depression leads to risk factors associated with cardiovascular problems, such as high blood pressure, high cholesterol levels, diabetes or a lack of exercise -- or if it's the other way around.
Results from the study indicate that changes in depression symptoms may also cause immediate physiological changes in the body, which in turn cause major cardiovascular problems to occur in the short term, but future studies are needed to further answer these questions.
Other researchers involved in the study include Kimberly Brunisholz, PhD; Benjamin Horne, PhD; Brent J. Muhlestein, MD; Tami Bair, RN; Donald Lappé, MD; Adam B. Wilcox, PhD; and Brenda Reiss-Brennan, PhD, APRN.
Intermountain Medical Center is the flagship facility for the Intermountain Healthcare system, which is based in Salt Lake City.