The Forest for the Trees: A Systems Approach to Human Health Research
Gohlke, Julia M., Portier, Christopher J., Environmental Health Perspectives
The current generation of children in many countries have a shorter life expectancy than their parents' generation, mainly due to changing sociopolitical systems and infectious diseases such as AIDS (World Health Organization 2006). Furthermore, the epidemiological transition that has occurred in developed countries leading to the modern rise in obesity, heart disease, type 2 diabetes, autoimmune disorders (Gillespie et al. 2004; Tedeschi and Airaghi 2006), and certain types of cancers (Dinse et al. 1999) has led to predictions of decreased life expectancy for future generations (Olshansky et al. 2005). This phenomenon cannot be explained by changes in human genetics because the time frame in which they have arisen or accelerated has hardly crossed a generation (Lopez and Murray 1998). Therefore, the sharp rise in these diseases can be attributed to recent changes in our environment, defined here as encompassing social, ecological, and physical components. Logically, identifying the environmental factors that are driving these increases should be a major focus of human health research. Unfortunately, this is not the case. Our continuing emphasis on individualized, therapeutic solutions in human health research has far-reaching implications for environmental and public health policy. We offer an alternative, systems-based framework to direct human health research integrating physical, ecological, and social factors with individual aspects.
Starting with Renee Dubos in the 1960s (Dubos et al. 2005) and continuing to present day (Anderson 2004; Cornish-Bowden 2006; Ebi and Gamble 2005; Rose 2001; Schwartz et al. 2006; Toscano and Oehlke 2005; Wing 2003), it has been recognized that a reductionist approach is not sufficient for predicting factors affecting human health, yet current human health research has continued to focus heavily on the biochemical processes causing and modifying specific disease states in the individual, rather than critical analyses of the environmental determinants of health. This focus is evident in analyses of citation indices (Boyack et al. 2005; Ioannidis 2006), where productivity, connectivity, and the role of high-impact multidisciplinary journals has been evaluated. For example, basic biomedical research fields--particularly biochemistry, neuroscience, immunology, cancer biology, and microbiology--have higher citation densities and higher publication rates in the highestimpact multidisciplinary journals, namely Nature and Science, when compared with interdisciplinary or population-focused research fields such as epidemiology, social sciences, and public health. In the United States, this result is not surprising considering that > 50% of National Institutes of Health (NIH)-supported grants have principal investigators at medical schools, traditionally focused on addressing disease paradigms and therapeutic solutions, whereas approximately 2% of NIH-supported grants have principal investigators in schools of public health, traditionally focused on addressing population risks (NIH 2005). Finally, the most cited medical research is increasingly funded by industry (Patsopoulos et al. 2006), highlighting the impact of current market forces, which provide large financial incentives in the search for therapeutic solutions. In contrast, complex behavioral interventions are not easily patented, so preventive research relies almost exclusively on public and nonprofit funding (Delaney 2006). The result is a research community that is very productive in medical areas dedicated to searching for therapeutic solutions for individuals with particular diseases, but limited in areas of research identifying preventive measures.
Our reliance on basic biomedical research approaches in human health research has undoubtedly shaped current policy decisions. Hence Paul Weiss's words, "It's one thing not to see the forest for the trees, but then to go on to deny the reality of the forest is a more serious matter" (Weiss 1969), are particularly salient. …