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Optimism, the general expectation that good things will happen and that the future will be positive, has been associated with better physical health outcomes in research across multiple methodologies and populations. This finding has attracted significant interest because it suggests that psychological dispositions may have consequences for biological processes in ways that extend beyond mental health. Evaluating the research on optimism and health requires attention to what is well-established, what mechanisms are proposed, and what remains uncertain or contested. The association between optimism and health outcomes has been documented in prospective longitudinal studies that measure optimism at one time point and track health outcomes over subsequent years. Research findings include positive associations between higher optimism scores and lower rates of cardiovascular disease, longer survival in cancer patients, lower mortality from all causes, lower rates of infection, and slower progression of HIV. These associations persist in analyses that control for depression, anxiety, and other psychological variables, suggesting that optimism has effects beyond simply the absence of negative psychological states. Several mechanisms have been proposed and studied through which optimism could affect physical health. Behavioral pathways are among the most direct: research finds that optimistic individuals engage in healthier behaviors including more physical activity, better dietary practices, higher rates of preventive healthcare use, and lower rates of substance use. If optimism produces health through healthier behavior, then interventions that change optimistic expectations might also change health behaviors and ultimately outcomes. Physiological mechanisms have been proposed based on research finding differences in biological markers between optimistic and pessimistic individuals. Studies find associations between higher optimism and better immune function, lower levels of inflammatory markers, different cortisol patterns, and more favorable cardiovascular profiles. These findings are consistent with the hypothesis that optimism affects health through stress-related biological pathways, possibly because optimistic individuals experience and respond to stressors differently than pessimistic ones, leading to less chronic physiological stress activation. The direction of causation in observational research on optimism and health is a genuine methodological challenge. Associations between optimism and health outcomes could reflect effects of optimism on health, effects of health on optimism as healthier people have more reason to be optimistic, or effects of third variables including genetics, socioeconomic status, and early life circumstances that affect both optimism and health. Longitudinal studies that control for prior health status address some but not all of these concerns, and the question of whether optimism is a cause or consequence of health differences is not fully resolved. Genetic contributions to trait optimism have been studied using twin methods. Research finds moderate heritability for optimism, meaning that genetic factors explain a meaningful portion of individual differences in optimistic outlook. This finding suggests that optimism is not purely a product of circumstances or learning, and it raises questions about the extent to which interventions can change dispositional optimism or whether they primarily affect momentary optimistic thinking rather than stable trait optimism. Interventions designed to increase optimism have been developed and studied primarily in the positive psychology tradition. Best possible self exercises, which involve writing about an ideal future in which life has turned out as well as possible, have shown positive effects on optimism and wellbeing in some studies. Research on whether increasing optimism through these exercises produces downstream effects on health behaviors or biological markers is limited and mixed. Whether the trait-level optimism associated with health outcomes in longitudinal research is the same construct targeted by brief positive psychology exercises is an important question the research has not fully resolved. Unrealistic optimism, which involves positive expectations that are inconsistent with objective probabilities, is a dimension of research that complicates simple advocacy for optimism. Research finds that most people are unrealistically optimistic in domains including personal health risk, occupational success, and relationship longevity, and that this unrealistic optimism can produce both benefits through reduced anxiety and harms through inadequate risk management and preventive behavior. The difference between adaptive optimism and unrealistic optimism that leads to poor decisions is an important distinction in both research and clinical contexts.

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''Originally published February 27, 2024 on [https://docmoates.com/blog/optimism-and-health-research-on-positive-expectations-and-physical-wellbeing/ docmoates.com].''