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Newsletter of the Society for Prevention Research
Spring 2013 , Volume 3, Issue 1

The Future of the Scientific Practice of Prevention
By Ralph Tarter

Ralph Tarter

Many summer afternoons were spent with my father in the cheap seats rooting for the Montreal Royals, then the triple A farm club of the Brooklyn Dodgers. My dad, like thousands of men, wore a white shirt, tie and fedora. Fast forward six decades, men today at the ballpark typically wear a tee shirt (if any), never a tie, and baseball cap (often pointed backwards). Changing norms pertaining to dress mirror relaxation of behavioral norms. Ubiquitous examples of currently normative behavior that were only recently beyond societal boundaries include “body art” (previously confined to criminals and sailors), babies born outside of marriage (currently the majority for women under 30), and ornamental jewelry skewered to many body parts apart from traditional earlobes. Attributions of these changes to “secular trends”, “birth cohort” or “historical period effect” do not account for the causes. Because prevention is modification of processes predisposing to a disorder, it is essential to understand the causes of the disorder for the intervention to be effective. This approach to prevention is consistent with the NIH Roadmap. Indeed, it is a cardinal principle medicine.

Prevention is directed at either averting expression of phenotypes comprising the prodrome (primary prevention) or disturbance portending the clinical disorder (secondary prevention). Since all biobehavioral characteristics (phenotypes) result from the environment impacting on the genotype, effective prevention thus involves modifying gene expression. The outcome of this intervention is the desired phenotype.

Within this framework, the concept termed individual norm of reaction is central to prevention practice. This concept asserts that the individual’s genotype predisposes to a range of phenotypes (e.g. IQ between 90 and 112). The person’s specific expressed phenotype (e.g., IQ = 103) is the result of the individual-specific environment affecting expression of the genotype so as to produce a cascade of biochemical reactions resulting in numerous neurobiological events that ultimately manifest as physiological and psychological traits. Clearly, this process is enormously complex. Nevertheless, the overarching effort in scientifically grounded prevention practice, albeit a daunting one, requires marshalling the appropriate environmental resources to potentiate development of desired phenotypes. However, because the range of possible phenotype outcomes (i.e. the individual norm of reaction) is set by the individual’s genotype, a discomforting reality is that the genotype may not have the potential to realize the desired outcome.

Let me illustrate: The average Dutch male is 6’1” tall. During the past 200 years mean height of Dutch men increased 7”. Because the genetic pool of the Dutch population has not changed within this period, the increased height is due to societal (environment) changes enabling previously unrealized genetic potential. Specifically, universal access to healthcare, food availability, policies preventing destitute poverty, social safety net that lowers stress (and consequent psychiatric and medical disorders), cultural norms fostering physical fitness (one quarter of the population are members of athletic clubs) and lifestyle emphasizing exercise (e.g. walking and bicycling) all contribute to the increase in stature. Dutch men are the tallest in Europe and surpass U.S. men by an average of four inches! Nevertheless, many Dutch men are shorter than the average American male. Hence, despite an environment that facilitates height, the genotype of many Dutch men prevents attaining even the average height of Americans. In effect, commensurate with the individual norm of reaction principle, the genotype constrains the benefit of the environment.

What does this mean for the scientific practice of prevention? Essentially, the answer is that prevention practice will avert disorders and diseases by engineering the environment tailored to the individual’s genotype to promote optimum phenotypes. This will be neither easy nor straightforward. There are ~20,000 genes with numerous functional polymorphisms. Since most disorders are polygenic, complexity is further magnified by gene-gene as well as gene-environment interactions. Nevertheless, there is reason to believe that this complexity can be managed using computers which today already have reached the network performance of quadrillions of operations per second. Ethical and policy considerations notwithstanding, prevention practitioners in the future will have an armamentarium of tools to potentiate impact of the environment on the genotype to promote desired biological and behavioral phenotypes.

You may have noticed that this future has arrived. If not, check out 23andMe.com (founded by Anne Wojcicki, the wife of Google co-founder Sergey Brin). Send this company some saliva and for a small fee your genetic risk for a variety of diseases or for an adverse reaction to some medications is estimated. The Federally-funded Person Centered Oriented Research Innovation Institute (PCORI) places human individuality at the center of the big question of “what works for who”. The International College of Person Centered Medicine, a network of scientific and professional societies (including the WHO) is one key organizational leader of this movement.

Having had the privilege of being present at the founding of SPR, I believed then as I believe now that prevention is essentially the practice of ecology. That is, the goal is to maximize a good fit between the individual and multiple environments within a lifespan framework. Adaptation conceptualized in this fashion is contingent on acquisition of a large array of biological and psychological characteristics (phenotypes) that are related to lowered risk of disease and disorder. Accordingly, the scientific practice of prevention will directly connect to an understanding of etiology, and as such, deploy environmental resources tailored to the individual genotype to maximize expression of optimum phenotypes.

This is the mission of SPR as I see it from my seat in the bleachers.

Ralph E. Tarter, Ph.D. is Director of the NIDA-funded Center for Education and Drug Abuse Research (CEDAR), Professor of Pharmaceutical Sciences at the University of Pittsburgh School of Pharmacy and a founding member of the Society for Prevention Research.

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Editor: Hanno Petras, PhD
Executive Director: Jennifer Lewis, CAE
Membership Director: DeeJay Garringo

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