Acute coronary syndrome-associated depression: the salience of a sickness response analogy?

Depression emerging in conjunction with acute coronary syndrome (ACS) is thought to constitute a distinct high-risk phenotype with inflammatory determinants. This review critically examines the notion put forward in the literature that ACS-associated depression constitutes a meaningful subtype that is qualitatively different from depressive syndromes observed in psychiatric patients; and evaluates the salience of an analogy to the acute sickness response to infection or injury as an explanatory model. Specific features differentiating ACS-associated depression from other phenotypes are discussed, including differences in depression symptom profiles, timing of the depressive episode in relation to ACS, severity of the cardiac event, and associated immune activation. While an acute sickness response analogy offers a plausible conceptual framework, concrete evidence is lacking for inflammatory activity as the triggering mechanism. It is likely that ACS-associated depression encompasses several causative scenarios.