New Study Examines Shared Neurobiology of Obesity and Addiction
A recent study examining the shared neurobiological substrates of obesity and addiction has concluded that “there are several identifiable circuits in the brain, whose dysfunctions uncover real and clinically meaningful parallels between the two disorders.” N.H. Volkow, et al., “Obesity and addiction: neurobiological overlaps,” Obesity Reviews, September 2012. According to the study’s authors, “Drugs of abuse tap into the neuronal mechanisms that modulate the motivation to consume food, thus, it is not surprising that there is an overlap in the neuronal mechanisms implicated in the loss of control and overconsumption of food intake seen in obesity and in the compulsive intake of drugs seen in addiction.”
In particular, the study considers brain dopamine (DA) pathways and their role in both obesity and addiction, cautioning that the current debate over “food addiction” often oversimplifies behavioral patterns involving environmental and biological factors. As a result, the authors seek to sidestep the debate by focusing on the neurobiological processes shared by obesity and addiction “that, when disrupted, can result in compulsive consumption and loss of control in a dimensional continuum.”
The findings ultimately suggest that “it is the discrepancy between the expectation for the drug/food effects (conditioned responses) and the blunted reward experience that sustains the drug taking/food overconsumption behavior in an attempt to attain the expected reward.” Individuals with disrupted brain DA pathways may thus experience (i) “an enhanced motivational value of the drug/ food…at the expense of other reinforcers”; (ii) “an impaired ability to inhibit the intentional (goal-directed) actions triggered by the strong desire to take the drug/ food…that result in compulsive food/drug taking”; and (iii) “enhanced stress and ‘antireward reactivity’ that results in impulsive drug taking to escape the aversive state.”
“The picture that is emerging is that obesity, similar to drug addiction, appears to result from imbalanced processing in a range of regions implicated in reward/ saliency, motivation/drive, emotion/stress reactivity, memory/conditioning, executive function/self-control and interoception, in addition to possible imbalances in the homeostatic regulation of food intake,” concludes the study. Additional details about lead author Nora Volkow’s work as director of the National Institute on Drug Abuse appear in Issues 106 and 233 of this Update.
