Psychological stress has been shown to increase activation of the sympathetic nervous system and the hypothalamic pituitary adrenal axis. This increased activation releases adrenaline, noradrenaline, and cortisol, which lead to faster heart rate, increased cardiac output, and narrower arteries. These changes, in turn, create increased blood pressure. Activation of these systems also accelerates the progress of atherosclerosis and can lead to acute plaque rupture, which results in ischemia of the heart (angina) and coronary heart disease and stroke.