Barefoot and colleagues suggested two possible mechanisms to explain the relationship between expectation and mortality. In the first, "Optimists have been found to be more likely to address the demands of a problem rather than withdrawing or focusing on its emotional consequences," a coping predisposition that may be more effective in reducing risk factor levels.
In the second, it's likely that pessimists experience "more tension and negative emotions," which translates to "heightened stress, autonomic dysregulation, and other physiological responses that increase the risk of cardiac events."
In their commentary, Gramling and Epstein noted that unbridled optimism "can be disastrous. Patients with serious incurable illness harboring unchallenged optimistic perceptions to choose burdensome treatments that they might not have chosen if they had a more balanced understanding of their overall prognosis."
Rather, they said, a better strategy would be to view both optimism and pessimism as not mutually exclusive, such as a "hope for the best, prepare for the worst," approach.