Abstract and Introduction
Abstract
Aims The nature of the association of depression and anxiety with risk for acute myocardial infarction (AMI) remains unclear. We aimed to study the prospective association of single and recurrent self-reported symptoms of anxiety and depression with a risk of AMI in a large Norwegian population based cohort.
Methods and results In the second wave of the Nord-Trøndelag Health Study (HUNT2, 1995–97) baseline data on anxiety and depression symptoms, sociodemographic variables, health status including cardiovascular risk factors and common chronic disorders were registered for 57 953 adult men and women free of cardiovascular disease. The cohort was followed up during a mean (SD) 11.4 (2.9) years for a first AMI from baseline through 2008. A total of 2111 incident AMIs occurred, either identified at hospitals or by the National Cause of Death Registry. The multi-adjusted hazard ratios were 1.31 (95% CI 1.03–1.66) for symptoms of depression and 1.25 (CI 0.99–1.57) for anxiety. Two episodes of mixed symptoms of anxiety and depression (MSAD), reported 10 years apart, increased the risk for AMI by 52% (11–108%). After exclusion of the first 5 years of follow-up, the association of depression symptoms with AMI risk was attenuated. Relative risk for AMI with anxiety symptoms and MSAD weakened when participants with chronic disorders were excluded.
Conclusion Self-reported symptoms of depression and anxiety, especially if recurrent, were moderately associated with the risk of incident AMI. We had some indications that these associations might partly reflect reverse causation or confounding from common chronic diseases.
Introduction
Depression and anxiety, both highly prevalent conditions in the general population, are associated with elevated risk for acute myocardial infarction (AMI). However, the nature of this association remains controversial.
One of the greatest challenges in the research on the prospective association of anxiety and depression with AMI is that atherosclerosis, one of the main underlying pathophysiological mechanisms of AMI, is known to develop during decades before the first clinical symptoms. However, almost all studies of depression included middle aged or older adults, often with a short follow-up time. Thus, individuals free from clinical heart disease in the aforementioned prospective studies may not be free from atherosclerosis, which may facilitate depressive symptoms even before generating ischaemia.
Furthermore, in most previous reports, the well-known cardiovascular risk factors were inadequately controlled for, and it is not clear to what extent these factors explain the observed association between depression and AMI. Among the most overlooked confounders are comorbid physical disorders. Depressive symptoms are highly correlated with the overall disease burden, and several common chronic disorders are also risk factors for AMI. Moreover, depression is known to have an episodic nature, yet in the great majority of previous studies, depression was assessed only once. Some studies, however, suggest that recurrent depression has considerably stronger association with AMI than single depressive episodes.
Further, anxiety and depression are often considered separate psychopathological conditions, yet they share common symptoms and often overlap. Still, relatively little data are available on the prospective association between anxiety and risk for cardiovascular disorders (CAD), and similar methodological concerns as those presented for depression apply to these studies as well. Therefore, the aim of this study was to investigate the prospective association of single and recurrent self-reported symptoms of anxiety and depression with the risk of AMI controlled for potential confounders, including comorbidities in a large population-based cohort.