People with alcohol use disorder (AUD) may not respond typically to images of food (i.e., cues), according to a novel study using brain imaging. AUD is believed to reshape the brain circuitry involved in reward and motivation such that alcohol cues become emphasized over natural (or conventional) rewards, including life goals, food, and social connections. Alcohol cues are thought to trigger an enhanced dopamine release, relative to cues of conventional rewards, among people who are vulnerable to AUD, which may amplify their risk for problematic drinking. Consistently, a heightened response to alcohol cues has been linked to craving, heavy drinking, and vulnerability to relapse. Natural cues, meanwhile, may become less salient with the disease progression. AUD is associated with both malnutrition—raising the risk for liver disease—and social and emotional deficits, which could, in turn, undermine treatment and recovery efforts. Increasingly, treatment researchers are using brain responses to alcohol cues as a measure for evaluating the effectiveness of AUD medications in development. Despite the potential importance of the relationship between alcohol cues and natural rewards, it remains generally underexplored. For this study in Alcohol: Clinical & Experimental Research, the investigators used brain scans to compare the reward processing of people with AUD and light drinkers to a range of visual stimuli.
Researchers at the Medical University of South Carolina worked with 28 adults (average age 32). Forty-three percent were women; most were White. Fourteen met criteria for AUD; 14 were light drinkers. All participants provided detailed information on their use of alcohol and other substances and gave blood and urine samples for corroboration. The participants underwent a functional magnetic resonance imaging (fMRI) scanning session. They viewed images relating to alcohol—using an established protocol known to activate reward circuits in the brain—as well as non-alcohol beverages (control condition). They also viewed images of food, household images (control condition), positive social scenes, and images of people involved in everyday tasks (control condition). Researchers also examined brain activation from MRI data and used statistical analysis to look for associations between neurological patterns and imagery in both groups. The participants also reported their experience and intensity of positive and negative emotions while viewing the various images following the scanning session.
The participants with AUD reported an average of 4–5 drinks a day in the last month; just over half of those days involved heavy drinking. Light drinkers reported less than 1 alcohol-containing drink a day. During the scanning session, their brain activation patterns were consistent with their self-reported emotional responses. Among people with AUD, food images elicited abnormally low reward activation in two brain regions. These regions—the superior frontal gyrus and the caudate—have roles in motivation and goal-driven behaviors. The lower response to food images within the superior frontal gyrus was, in turn, linked to more recent heavy drinking days among AUD participants and higher craving and alcohol dependence across the whole sample. The groups’ reactions to social images did not differ significantly.
Heavy drinking appears to be associated with a reduced response to natural rewards, specifically food. These study findings are preliminary and may not generalize to other populations. If substantiated, they may point to an opportunity for enhancing natural brain reward activation as a treatment for AUD and co-occurring conditions. It is unknown whether reduced interest in food precedes or is caused by AUD.
Blunted reward-related activation to food scenes distinguishes individuals with alcohol use disorder in a case-control fMRI study. W. Mellick, L. McTeague, S. Hix, R. Anton, J. Prisciandaro. (Pp xxx)
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