Depression Negates Benefit of Heart-Healthy Behaviors

Megan Brooks

March 28, 2013

Untreated symptoms of depression can negate the anti-inflammatory benefits typically associated with physical activity and light to moderate alcohol consumption, new research suggests.

Based on measurements of the cardiometabolic risk marker C-reactive protein (CRP), the study "points to a new role for depression in addition to its direct impact on physical and mental health," lead author Edward C. Suarez, PhD, associate professor of psychiatry and behavioral sciences at Duke University School of Medicine, Durham, North Carolina, told Medscape Medical News.

The results suggest that depressive symptoms can "minimize the health effects of what many Americans are doing to reduce our risk for heart disease and type 2 diabetes — exercise more and adopt a Mediterranean-type diet that includes light to moderate alcohol consumption," Dr. Suarez said.

The study was published online March 26 in Brain, Behavior, and Immunity.

Novel Findings

Light to moderate alcohol intake and leisure-time physical activity are independently associated with lower levels of CRP, whereas depression has been associated with elevated CRP.

Dr. Edward Suarez

The investigators assessed the moderating effect of depressive symptoms, using the Beck Depression Inventory, on leisure-time physical activity and light to moderate alcohol intake in 222 healthy nonsmoking men and women aged 18 to 65 years with no history or diagnosis of psychiatric conditions.

They recorded the amount of alcohol consumed, defining light to moderate drinking as about half a drink per day for women and 1 drink daily for men. They also recorded the amount of physical activity the participants logged in the past week, such as walking, playing tennis, and going to exercise classes. Fasting blood samples were used to measure CRP and lipids.

The researchers found that individuals who were physically active generally had lower levels of CRP, with the exception of those with depressive symptoms (4.5% of the cohort), who reaped no beneficial effect of physical activity on CRP levels.

They also found that light to moderate alcohol consumption was associated with lower CRP, but only in men who were not depressed. Light to moderate alcohol consumption was not associated with lower CRP in those with increased depressive symptom severity, the researchers say.

The effect seems to be specific to inflammation as measured by CRP, given that depression did not affect other health markers, such as fasting triglyceride or cholesterol levels, the investigators note.

"To my knowledge, these are novel findings," Dr. Suarez told Medscape Medical News. "While there has been preliminary evidence to suggest that psychological distress impacts the response to vaccination in older adults, we know of no other study that has examined the impact of depressive symptomatology on the anti-inflammatory benefits of leisure time physical activity and light to moderate alcohol consumption," he said.

"These findings argue for medical providers to combine management of depression alongside reduction of other forms of cardiovascular risk, instead of the more traditional approach of managing conditions separately," the authors conclude.

"We're not saying that exercise isn't helpful for those with depression; what we saw is that depression has effects beyond what has previously been reported. Even if mental health improves, the anti-inflammatory benefits of physical activities may lag behind," Dr. Suarez commented in a statement from Duke.

"Remarkable" Finding

The fact that this study is large and includes both men and women is "important," Martica Hall, PhD, associate professor of psychiatry and psychology and clinical and translational science, Western Psychiatric Institute, University of Pittsburgh Medical Center, Pennsylvania, told Medscape Medical News.

"The other thing that is striking about their results is that these were really healthy people; they didn't have a psychiatric history, they weren't taking antidepressant medication, and they were heart healthy. And yet they found this interaction, and that's pretty remarkable," said Dr. Hall, who was not involved in the study.

She said it is also worth noting that the depressive symptoms were in a "very low range, and even so, men and women don't appear to reap the health benefits of light leisure-time physical activity, and men don't get the benefits of moderate alcohol consumption, which has been associated with heart health."

The reasons for the findings are unclear. "One could speculate that physiologic correlates of depression might be interacting to buffer the effects of these positive behaviors," Dr. Hall said.

"As a sleep researcher, I wonder if maybe part of it could be due to poor sleep among people with symptoms of depression that are starting to bubble up."

The investigators "hope to collaborate with cardiologists at Duke to test whether physical activity, which is recommended to cardiac patients, reduces inflammation among patients who are and are not depressed. It may be that while physical activity improves symptoms of depression in cardiac patients (results shown by a Duke study), the biological benefits are not realized."

Dr. Hall said this is "absolutely" worth studying further.

The study was funded by the National Heart, Lung and Blood Institute. The authors and Dr. Hall have disclosed no relevant financial relationships.

Brain Behav Immun. Published online March 26, 2013. Abstract