The possible role of seasonal mood changes in the seasonal distribution of acute myocardial infarction.

Abstract

TO THE EDITOR: A recent observational study suggests that there is a seasonal pattern in the occurrence of acute myocardial infarction that is characterized by a marked peak of cases in the winter months and a nadir in the summer months. 1 This pattern was observed in all subgroups analyzed as well as in a different geographic area. Previously, many studies reported increased mortality from coronary heart disease during the winter months. The effects of depression on patients with coronary heart disease are well documented. 2,3 Almost all recent studies reported increased cardiovascular morbidity and mortality in patients with depressive symptoms. Depression has been implicated as an independent risk factor in the pathophysiologic progression of cardiovascular disease. Many persons experience seasonal changes in mood and behavior. 4,5 The degree to which seasonal changes affect mood and behavior has been called “seasonality.” 4 Seasonality can manifest to different degrees in different persons. Seasonal affective disorder, a condition in which depressive episodes in fall and winter alternate with nondepressed periods in the spring and summer, is an extreme form of seasonality. 5 Because depressive disorders affect the pathophysiological progression of cardiovascular illness, persons with high levels of seasonality may be at increased risk of developing acute myocardial infarction during the winter months. Possibly, seasonal mood changes contribute to the increased incidence of acute myocardial infarction in the winter. This hypothesis has practical applications. First, patients with cardiovascular disease who have seasonal mood changes should be identified and get the appropriate treatment (light therapy, etc.) that may improve the quality of life for these persons and reduce their incidence of acute myocardial infarction; and, second, these patients may need more careful medical management during the winter months. Studies of the effects of seasonal mood changes on cardiovascular system are merited.