Researchers Examine Parallels Between Food and Drug Addiction

A recent article published in Biological Psychiatry reviews the research examining the neurological basis for food addiction and its relation to obesity. Nora Volkow, et al., “The Addictive Dimensionality of Obesity,” Biological Psychiatry, February 2013. Co-authored by National Institute on Drug Abuse Director Nora Volkow, the article proposes that drug and food addiction “share neurobiological processes that, when disrupted, can result in compulsive consumption, while also involving unique neurobiological processes.” In particular, the authors argue not that obesity is the result of food addiction, “but rather that food reward plays a critical role in overeating and obesity, referring to it as the dimensional component of obesity.”

To this end, the article describes how drug and food addiction allegedly
share genetic, molecular, neurobiological, and behavioral mechanisms that,
when coupled with environmental triggers, have “the potential to facilitate
or exacerbate the establishment of uncontrolled behaviors.” The authors also
speculate that exposure to obesogenic foods can trigger what is known as
“the dark side of addiction,” “the transition that drug-addicted individuals
experience between the initial, pleasurable use of drugs to the one that, with
repeated use, results in drug consumption to relieve negative emotional
states.”

“Thus, strategies that borrow from successful prevention and treatment
strategies in addiction might be beneficial in obesity,” suggest the authors.
“Future research in this area should include social and policy strategies to
decrease the availability of obesogenic food (restricting its sales, increasing
their costs), increase access to alternative reinforcers (healthy food that can
compete in price for high-calorie food and access to physical activity), and
develop education (taking advantage of schools, families, and communities).”
Additional details about Volkow’s food addiction research appear in Issue 456
of this Update.

Meanwhile, the latest volume of Academic Press’s Vitamins and Hormones
series includes a chapter outlining the potential role of the gastric peptide
ghrelin in obesity and food addiction. Harriët Schellekens, et al., “Ghrelin
at the Interface of Obesity and Reward,” Obesity (Vitamins and Hormones),
February 2013. Published in the first edition of Obesity, the chapter discusses
ghrelin “as the only orexigenic hormone from the periphery to act in the
hypothalamus to stimulate food intake,” describing “a role for ghrelin and its
receptor at the interface between homeostatic control of appetite and reward
circuitries modulating the hedonic aspects of food.”

Focusing on ghrelin-mediated appetite signaling, the chapter specifically
argues that “nonhomeostatic factors such as the rewarding and motivational
value of food, which increase with food palatability and caloric content, can
override homeostatic control of food intake” and can lead to overconsumption.
Relying in part on research conducted by Volkow, the article also posits
that “[t]he repeated overconsumption of palatable (i.e., pleasurable) foods
shares many characteristics with addictive behaviors” and is accompanied by
“neuroadaptive changes within the central reward circuitries, such as altered gene expression and altered brain responsivity to food, similar to those occurring upon drug dependence.” As a result of these findings, the authors
ultimately conclude that future food addiction research and treatments
may focus on “novel therapeutics” designed to target “the ghrelin-mediated
reinforcing effects of palatable foods and drugs of abuse.”