Chronic mental stress can come in a variety of forms, and may originate in the external environment, as an interaction between the individual and the environment, or from within the individual. Examples of things causing mental stress include earthquakes, job stress, and several measures of negative affect; all have been shown in prospective studies to have adverse effects on the development of hypertension and coronary artery disease. After the Hanshin-Awaji earthquake in Japan, there were increases of blood pressure and deaths from myocardial infarction that persisted for several months. Job strain, which is defined as a combination of low control and high demands at work, has been associated with increased blood pressure and coronary heart disease outcomes, particularly in men. Negative affect, which may manifest itself as depression, anxiety, anger, or hostility, has similarly been related to hypertension and coronary heart disease. Depression is emerging as the most important component with respect to cardiovascular disease. A common link for all these factors is a perceived loss of control over one's environment.