Challenging Dogma - Fall 2007

...Using the social and behavioral sciences to improve the practice of public health.

Monday, December 10, 2007

Ways To Incorporate Genetics, Environmental Factors, And Policy To Create Comprehensive Care To Combat The Obesity Epidemic- Jody E. McLean

Obesity is a health care epidemic in America. To combat this, many national and community public health intervention have been launched. However, obesity is a multi- factored problem which includes genetic and environmental components that can both be linked to behavior. Genetics is an emerging part of science with huge implications for public health. Currently, the discoveries such as BRAC1 and BRAC2 (breast cancer genes) which at risk women can be tested for and CKR5 (chemokine receptor gene) that protect 1% of the population from HIV have significant public health implication. Public health clinicians can work with current medical and environmental interventions to infuse them with knowledge of genetic susceptibility (1). Environmental changes over the past twenty years have been linked to the 61% increase in the obesity rate of adults (2). Currently, there is comprehensive care which includes many medications, public health interventions, and health care options for at risk patients and populations. All these options can be critiqued using social and behavioral science models. Though the heritability of obesity can not be ignored, it should be used along with environmental information to tailor a comprehensive care plan for at risk patients and populations.
Argument I: Genetic Information
Genetic information about obesity must be used to gain knowledge to tailor in comprehensive care for at risk patients as well as populations. There are a few isolated ethnic groups with a rare gene predisposition to the obesity gene (3). However, obesity is not a simple disorder with a one to one relationship to a genotype or mutation that can be related to large populations. Heritability is a genetic term that describes the ratio of phenotypic variance in the population that is attributable to genetic variance and/or the extent to which genetic individual differences contribute to individual differences in observed behavior (4). Identical and non identical twin studies reported that heritability of BMI to be between 40% and 70 %(2). These studies are done with separated twin pairs indicating that despite environment, BMI is highly heritable.
Heritability is associated with feeding behaviors. Forty-six percent of meal eating variance is accounted for by genes. Also, fifty-six percent of the variance in the amount that is eaten at meal is associated with genes (4). Thus, half of feeding behaviors are hard wired in our genes. There is even a pathogenic heterozygous mutation in the MC4R that is found in 1-6% of severe patients with obesity. Lack of MC4R activation is associated with increase intake of food or binge eating(4). There are other genes associated with body weight, fat distribution, adiposity, food intake and diet induced obesity (5). Due to their distribution over several genes, more research has to be done in order to quantify this beneficial information.
Genetic information affects an individual's perception of themselves and their ability to deal with their weight issues, especially when their family has a history of weight problems. Thus, it would be imperative to assess how genetic information affects perceived susceptibility and self-efficacy. Many health interventions rely on individual behavior change models such as the Health Belief Model (HBM). This model focuses on the perceived susceptibility, severity, barriers and benefits towards the likelihood of the action (6). However, genetic predisposition to increase energy intake is not a perceived barrier it is a quantifiable/actual barriers. Regarding obesity, the HBM fails to consider varying physical, mental and genetic make up of individuals that are not perceived and therefore effect their ability to achieve their outcome. Genetics could be better taken into account using behavior theory such as Reasoned Action (6). Knowledge of predisposition to an increased BMI could negatively affect whether or not a person thought they could change their behavior to reach an outcome. Alternatively, it could encourage people to make reasonable behavior changes to reach a specific achievable goal. It is important to acknowledge the genetic component to aid patients in creating a reasonable strategy to increase their belief that they can reach a desired outcome.
Argument II: Environmental information
Environmental information about obesity must be used to gain specificity in comprehensive care for at risk patients and populations. Changes in the American lifestyle in the last twenty years have created a toxic environment, including increases in unhealthy eating habits. From 1970 to 1994 American’s energy intake has increased by 15% (4). There has been an increase in portion sizes, fast food restaurants, access to energy dense foods in schools; increase of labor saving devices and a decrease in cost of fast food combined with physical activity in school contribute to a toxic environment. In addition, parents longer work hours leaves less time to cook and supervise their children’s activities. All the above changes affect adults and children across all social strata (4). These components also give direct routes to possible intervention on a national scale. People in lower social strata have fewer resources and have an increased risk for weight gain. These populations have to negative influences such as higher exposure to fast food outlets, limited area to partake in physical activity, poor knowledge of health and nutrition, less access and affordability of more nutritious foods which all influence energy intake and expenditure (4). Knowledge of what is lacking in American’s diet, the abundance of fast and unhealthy food options, and lack of activity are direct routes to interventions. There are many environmental factors to be assessed, but not all behavioral models are appropriate. The HBM applied to individual’s perceived assessment does not acknowledge the increasing toxic environment that increases absolute susceptibility. In this case, it is better to use other models when assessing environmental causes and possible interventions. Social Cognitive Theory gives equal balance to personal factor, environment factors, and behavior (class). By assessing a patient self’s efficacy and environmental factors, clinicians can tailor treatments to combat behaviors that have lead to increased weight gain. When creating a national or community based campaign, a well executed use of Social Learning Theory would be most beneficial in assessing the environmental effects that cause the behavior (6). By observing communities through a member of the community, we can gain knowledge of the barriers people face when trying to change their behaviors. Using the appropriate social science models can help medical clinicians to create individual treatments and public health professionals to create population based interventions and policy.
Argument III :Policy
Current public health interventions/policy and treatments fail to incorporate genetic information. There is no mention of genetics in the Federal Obesity Clinical Guidelines pertaining to the clinical relationship (7). These guidelines were issued in 1998 by the National Institutes of Health and have not been updated since. Nowhere on their website (healthierus.gov) was genetics even mentioned. In the Surgeon General’s Call to Action to prevent and decrease overweight and obesity released in 2001, there is no mention of genetics in the research and evaluation section. However, genetics could be grouped into research done to “develop and disseminate best practice guidelines” (8). Clearly, genetics is not the sole answer to obesity, but can contribute to understanding the behavior that lead, to increased weight gain. Doctors and clinicians should be weighting BMI and waist measurements along with family history and eating behaviors. Information about genetic possibilities should be available to anyone treating obesity patients to help tailor their treatments. Since genetics and environmental factors are intertwined treatments and should be they included in family/community interventions to combat an epidemic.
There are many national programs to weed through the focus on nutrition or physical education. In the Surgeon General’s action for preventions of obesity, five out of the eight points for action are community based suggestion rather than individual (8). These calls to action all require funding because there is implementation on a community level. Different communities have varying amounts of money to allocate to services. Thus, what part of the community is the federal government already funding and/or could easily create incentive? Community based changes, including school and worksite, are direct ways for the government to affect the majority of American’s environments. As the school lunch program is funded by the federal government, they have to improve their policies that dictate the standard of the food offered. The government can facilitate improvements the workplace interventions by offering tax cuts to employers. Work site interventions can be more affective than school interventions. Since parents are the head of household they are more likely to change the whole families’ behavior. Worksite interventions can be offered repeatedly, thus increasing the “likelihood of motivating behavior change in persons who are at various stages of readiness”(9). Worksite intervention can also be tailored to the particular environment and address the barrier that affect an employee and their family. Many policy changes need to happen on a community level rather than national to truly have an affect on environments.
There is a connection that can be made between the environmental and genetic components of obesity. Community based projects create a maximum effect on environment. Doctors and clinicians need to incorporate family history into diagnosis and treatment since genetic information relates is complementing, to information about BMI, food intake, and environment factors. A predisposed person will require intervention plus greater support to meet their goals and maintain a healthy weight (10). Doctors can use environmental information to connect their patient to community and family based intervention along with standard individualized care. To combat obesity on a national level, school, worksite and community based interventions are the best way to make effective changes in the environment.
Genetic information about obesity provides more specific care through either understanding behavior or predisposition to increased BMI. The toxic environment of today has increased the barriers to obtaining a healthy weight. The Federal government has created guidelines to combat the increase in obesity. Public Health professionals can take clinical and scientific research information on genetics, then create strategies for population based preventions to incorporate genetics with environmental guided by current policy. Use of the social behavior models can guide incorporation of environmental and genetic factors. Most importantly, Public Health professionals have to educate the general public as well as clinicians to encompass all modes of health (1). Genetics is a useful tool for Public Health professionals now and in the future to help combat many health issues on a individual and national scale.
References
1.Khoury, Muin J. “Genetic Epidemiology and the Future of Disease Prevention and Public Health.” Epidemiologic Reviews. 1997;19;1:175-180.
2. Anderson, Laurie H “Public health Strategies for Preventing and Controlling Overweight and Obesity in School and Worksite Settings” 7 October, 2005.
3. Commuzzie, Anthony G. et al “The Search for Human Obesity Genes.” Science. 1998;280:1374-1377.
4.Hernandez, Lyla and Blazer, Dan. “ Genes, behavior and the Social Environment: Moving Beyond and Nature/Nurture” Washington DC: Institute of Medicine of the National Academies. 2006.
5. Barsh, Gregory S at et. “Genetics of body-weight regulation” Nature. 2000;404:644-651.
6. Choi, Kyung-Hee et al. “ HIV Prevention Among Asian and Pacific Islander American Men Who Have Sex with Men: A Critical Review of Theoretical Models and Directions for Future Research.” AIDS Education and Prevention. 1998:19-26.
7. “First Federal Obesity Clinical Guidelines Released “ National Institutes of Health. http://www.nhlbi.nih.gov/new/press/oberel4f.htm. 17 July, 1998.
8. “The Surgeon General’s Call To Action To Prevent and Decrease Overweight and Obesity” United States Department of Health and Human Services . <http://www.surgeongeneral.gov/topics/obesity/calltoaction/fact_vision.htm> 2001.
9. Sorensen Glorian at et. “Increasing fruit and Vegetable Consumption through Worksite and Families in the Treatwell 5-a Day Study.” Am J of Public Health. 1999;89:54-69.
10. “Obesity and Genetics:What We know, What We Don’t know and What it Means”
http://www.cdc.gov/genomics/training/perspectives/files/obesknow.htm 8 June 2007.

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