reverse causation or omitted determinants of both education and health. The second question refers to the mechanism by which education improves health results. While the simplest explanation is that more educated persons are more knowledgeable about how to improve and maintain their health status and are better able to respond to health problems, there are other explanations. These include the effects of education on access to the healthcare system (for example, through higher income) or effects of education on increasing consideration for the long-run consequences of present behavior and taking preventative measures.
To answer the first question, health economists have relied increasingly on the use of instrumental variables techniques to isolate the exogenous effects of education on health outcomes. Following the studies on education and labor market outcomes, they have used externally imposed differences in compulsory schooling such as changes in compulsory attendance requirements that affect the amount of education attained. To control for genetic factors and family backgrounds, they have also compared the health of siblings who have different educational attainments. Lochner (2011) provides a recent review of the latest set of studies employing these sophisticated methodologies. His preferred set of 39 estimates shows a wide range of estimates of education effects on mortality, self-reported health, and disability, as well as two health-related behaviors—smoking and obesity. Not all of the estimates are statistically significant, and some have the wrong signs. By and large, the links tend to be stronger in U.S. than European studies.
With respect to trying to isolate the mechanisms by which education influences health outcomes and behavior, the relations are less clear. There is some evidence that both the general cognitive capabilities of more educated persons as well as specific knowledge contributes to this relation. Cutler and Lleras-Muney (2010b) have also attempted to decompose the education-health nexus into major components including differences associated with education, socioeconomic status and income, and access to social networks. They find that about 30 percent of the education-health gradient is due to a combination of the advantages of income, health insurance, and family background associated with more education; 10 percent is due to the advantages of social networks; and about 30 percent is due directly to education. They also explore the educational mechanisms that might account for the relationship. They conclude that it may not be the specific health knowledge conferred by education as much as greater interest and trust of science and general skills such as critical thinking and decision-making abilities, analytic abilities, and information processing skills that enable educated individuals to make better health-related decisions. Such mechanisms as risk aversion and longer-range time considerations (low time discount rate) do not seem to have substantial support in explaining the health gradients.