Are a family history of alcoholism and obesity related? A new study suggests a possible connection between the two.
The study, conducted by researchers at Washington University in St. Louis, found that a family history of alcoholism might put people at higher risk for obesity (Arch. Gen. Psychiatry 2010;67:1301-8). The researchers conducted an epidemiologic study looking at data from two nationwide surveys of noninstitutionalized adults: the National Longitudinal Alcohol Epidemiologic Survey of 1991-92, and the National Epidemiologic Survey on Alcoholism and Related Conditions of 2001-02. They found an association between body mass index and family history of alcoholism. This association was stronger in 2001 than in 1991, and was particularly striking among women. Such a trend suggested that something in the environment had changed.
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High-calorie foods can trigger the same reward response in the brain as addictive drugs or alcohol, researchers say.
We do know that in recent years, processed foods that are made with high levels of salt, sugar, and fat have become increasingly available. The contemporary American diet, although particularly palatable, seems to act as a type of "drug" in people who have higher sensitivity to rewards. Such high-caloric foods apparently can activate the same brain reward circuits as do drugs of addiction.
This basic idea of obesity and drug addiction that involves similar mechanisms has been around for a few years now. A 2008 study published in the Philosophical Transactions of the Royal Society of London, for example, used PET to compare brain activation in healthy controls, people addicted to drugs, and people who are obese (Phil. Trans. R. Soc. B 2008 Oct. 12 [doi:10.1098/rstb.2008.0107])). They found that the reinforcing response to drugs and food were both modulated by dopamine-2 (D2) receptor availability in the striatum. Low D2 receptor availability in the striatum of obese subjects was associated with decreased activation in the prefrontal cortex involved in inhibitory control – a pattern similar to that found in alcoholics.
Yet another study using a measure of sensitivity to reward, overeating, food preference, and BMI found that sensitivity to reward in healthy adult women was positively associated with preferences for foods high in sugar and fat (Appetite 2007;48:12-9). Drug addiction and food addiction have common properties: Both are affected by stress and involve reward systems, motivation, learning, inhibitory control, emotional regulation, and decision making (Nat. Neuroscience 2005;8:555-60). In fact, those characteristics have prompted researchers to suggest that obesity be considered a mental disorder in the DSM-V (Am. J. Psychiatry 2007;164:708-10; Medical Hypotheses 2009;73;892-9).
SIOUI MALDONADO BOUCHARD
But why did the epidemiologic studies find a particularly strong association between family history and alcoholism in women? The researchers did not go into much detail about this. The link remained after researchers controlled for sociodemographic differences, smoking status, and alcohol consumption, and was somewhat attenuated by control for major depression. The authors, therefore, suggested that psychiatric comorbidity might at least partly mediate the association between family history of alcoholism and obesity. We might speculate that because women generally are more sensitive to reward (Appetite 2005;45:198-201), exposure to high-calorie diet options available in the United States might have a stronger effect on them than on men. Also, it might be that food is less socially restricted than is alcohol for women. As a result, women who otherwise would not abuse alcohol might now be developing an addiction to previously nonexistent, highly processed, highly palatable foods.
Therapy-based programs similar to those for drugs of addiction and alcoholism – such as 12-step programs, incentive motivation, or cognitive-behavioral therapy – are already used for obesity. Pharmacologic treatment that targets the reward systems of the brain also might prove useful.
It is time for psychiatrists, primary care physicians, and endocrinologists to begin approaching obesity as more than just a metabolic disorder – for women in particular. In doing so, therapeutic interventions must be developed that target inhibitory control, the reward system, conditioning, and the drive for consumption.
Ms. Bouchard is pursuing a PhD in behavioral and cellular neuroscience at Texas A&M University in College Station. She has no conflicts of interest to disclose.