Life change patterns prior to death in ischaemic heart disease. A study on death-discordant twins

Abstract

IN RECENT years several studies have demonstrated that essential changes in the psychosocial situation may precede various manifestations of ischaemic heart disease (IHD) such as myocardial infarction [l-2] and sudden death [3]. It has been suggested [4-51 that a psychosocial change could trigger the development of a myocardial infarction. However, the meaning of such a change is closely connected with the personality of the individual [5]. Studies by Rosenman and Friedman [6-81 have shown that men with a certain personality or behavior pattern (labelled Behavior Pattern Type A and characterized by excessive sense of time urgency, enhanced aggressiveness and competitive drive) were significantly associated with an increased prevalence and incidence of IHD. These personality traits are probably partly inherited [6]. The question now arises whether the psychosocial changes reported prior to the onset of various IHD catastrophes [l-3] simply reflect a certain behavior pattern or whether the life changes may be independent risk factors for IHD. The difficulty inherent in such questions may be illustrated by a quotation from BiGrck 191: “some of the difficulties in the study of environment, as separated from the genetic equipment, derive from the fact that a certain environment may be a factor of selection attracting those with a certain kind of genes; or those with a certain genetic equipment may favor, and therefore seek, a special environment. Thus, a mutual interaction between the two factors does occur”. Therefore, studies on twins could be of great interest with regard to psychosocial factors and IHD because it would be possible to control the hereditary influence. Monozygotic (MZ) and dizygotic (DZ) twins probably also share environmental factors to a higher degree than other subjects.