Recent reviews substantiate the importance of depression in both the etiology and progression of coronary heart disease.1,2 The veracity of the relationship is also acknowledged in statements made by organizations involved in developing guidelines for cardiac rehabilitation (CR) and secondary prevention (SP) programs. These statements contain recommendations that include screening for depression using standardized instruments at CR intake and discharge, appropriate referrals to mental health professionals when depression is clinically significant, and follow-up with primary care providers.3,4 The AHA/AACVPR recommendations also promote the development of supportive rehabilitative environments that will enhance social support for CR patients and families. Thus, although providing definitive diagnosis or standard treatment for clinical depression (antidepressant medication or cognitive behavioral therapy) is beyond the purview of most CR and SP programs, screening for depression, providing referrals, and fostering socially supportive rehabilitative environment for vulnerable patients who may be at increased risk because of depressive symptoms are consistent with the goals of SP in heart disease.

The research projects presented by Joesephson et al and Dunn et al in this issue confirm the importance of screening for depression. In exploring the associations among depression, hopelessness, and various patient characteristics, Dunn and colleagues analyzed cross-sectional data from telephone interviews of 525 patients with acute coronary syndrome, which were conducted at an average of 14 days posthospitalization. They found a substantial vulnerability in that more than a third of the sample had scores suggesting the presence of depressive symptoms, and more than a quarter of the sample met the criteria for moderate to severe hopelessness. Moreover, depression was associated with being female, having a history of depression, and being unmarried, while hopelessness was associated with being unmarried, having lower education, and having undergone invasive procedures.

Joesephson and colleagues analyzed prospective data from a CR clinical database where, consistent with AACVPR recommendations, 402 patients were screened for depression at enrollment and after completion of a phase II CR program. At the 12-week follow-up, they found significant improvements in depression scores (drop of 30%) among those who completed CR and distinct differences between the sexes at baseline and 12 weeks, with women demonstrating higher depression scores than did the men at program entry and larger improvements in mean depression scores at program completion. The authors note that this pattern of sex-based differences in depression is consistent with other evidence, suggesting that women are at a greater risk for depression than men. The authors speculate that exercise may have contributed to improvements in depression scores, although they also note that without a control group, the improvement in Beck Depression Inventory depression scores cannot be attributed to CR completion alone. To be sure, a control group of non-CR participants would help determine if CR was responsible for improvements in depression, but these data come from a clinical database, not from a research study. Moreover, other components of the program besides exercise may have played a role in reducing depression scores. However, without knowing which components comprise the Summit Health CR program, it is difficult to attribute improvement to exercise alone.

Despite some methodological limitations in study designs, recent reviews suggest that exercise may be an effective treatment for depressive symptoms and/or major depression among adults,5-7 more particularly among adults with coronary heart disease.8 Interestingly, one commonly sited design limitation is the failure to control for/or measure "social interaction" among participants in the various comparison groups. Thus, when an exercise intervention is delivered in a group-based format, it would be difficult to attribute benefits to exercise alone when other variables, such as social interaction, may play a significant role in alleviating symptoms of depression. By way of illustration, in a study assessing the adjunctive benefit of exercise on depression and depressive symptoms, Abt9 randomized 31 participants undergoing standard treatment for depression to either a 6-week exercise group intervention or a non-exercise social control group (stress coping intervention). To control the influence of social interaction on outcomes, both groups met for the same amount of time each week. Although both groups showed significant improvements in depression measures, contrary to predictions, there were no differences in the level of improvement between groups, despite significant differences in exercise levels. Consequently, the authors were left with the speculation that it may have been the comparable levels of social interaction (1 hour, twice a week) that accounted for the improvement in depressive symptoms.

Others have mentioned the importance of controlling for social interaction when studying the effects of exercise on depression.10,11 As noted in the 1995 Clinical Practice Guidelines for Cardiac Rehabilitation, "Studies of exercise rehabilitation as a sole intervention are confounded by the consequences of group interaction, formation of social support networks, peer and professional support, counseling, and guidance, all of which may affect depression, anxiety, and self-confidence."12 Therefore, although researchers testing the effects of exercise on depression would be wise to control the effects of social interaction among subjects, CR clinicians may want to consider enhancing social interactions among participants. That is, practitioners might reflect on evaluating and possibly reformatting their rehabilitation and SP programs in a manner that maximizes opportunities for participants to engage in the kind of social interaction associated with reducing cardiovascular disease through reductions in symptoms of depression.

How might social interaction be enhanced in CR and SP programs? One basic strategy would be to design CR program implementation using a cohort-based model of service delivery whenever feasible. In this model, participants go through initial enrollment and assessment procedures individually so that goals are tailored to the specific needs of each patient. However, whenever possible, remaining components of the program are delivered to a group of patients whose membership remains essentially the same throughout the remainder or the program. Thus, each person engages in rehabilitation sessions (education, exercise, etc) alongside the same group of peers, thereby maximizing opportunity for the development of mutually supportive relationships based on shared challenges and goals. After only a few sessions, participants may begin to develop a sense of "we-ness," or a sense that "we are all in this together," resulting in a sense of belonging or cohesiveness known to have beneficial effects on depression.13-15 However, providing an environment that fosters a psychological or emotional sense of community and belonging among members of CR cohorts is probably far more likely to occur if group support is also a distinct component of the CR program. Ideally, the groups will be facilitated by professionals familiar with the principles of group dynamics in order to promote an atmosphere of safety and acceptance for all members. Others have asserted that psychological support groups run by trained psychologists should be a stand-alone component of CR.16,17 Similarly, Billings and colleagues18 recommend that support group sessions should be structured in a manner that teaches participants important communication skills, such as the identification and expression of one's own feelings and listening to and expressing empathy and compassion for others. They also view the group leader's primary role as one of promoting a sense of connection among group members.

New findings from a cohort-based SP program merit our attention. The Multisite Cardiac Lifestyle Intervention Program is a multisite lifestyle modification program (very low-fat diet, exercise, stress management, and group support) for individuals with or at risk for heart disease.19 The program model implements a cohort-based format, spouses are encouraged to participate in all program activities, and group support based on the Billings model noted above plays a central role in the program execution. A recent comparison of baseline to 12-week outcomes among 1,230 participants from 21 hospital sites revealed that in addition to improvements in medical risk factors, depression scores decreased dramatically from baseline (reductions ranged from of 34% to 48%, depending on different age groups), with an average drop overall of 46% (Sumner, personal communication). Again, attribution of causality is prevented by the absence of a control group. However, a clinical program that presents improvements in depression scores of this magnitude could not only be of interest to CR and SP clinicians but may also be relevant to designers of future clinical trials, such as ENRICHD, where seeking to determine the effects of efficacious depression treatments on cardiovascular disease morbidity and mortality are being tested.

Research has suggested that exercise, the primary component in CR programs, can reduce symptoms of depression. Meanwhile, we are also learning that marshalling social connectedness among participants in CR and SP programs may also help alleviate depression symptoms. To the extent that multifactorial CR programs comply with the guidelines and recommendations noted in the beginning of this editorial and also foster an environment of mutual support, encouragement, and sense of community, the follow-up scores on depression and other known cardiac psychosocial risk factors (hostility/anger, anxiety, and social isolation) may be even more favorable.

References