A Preliminary Study of the Human Brain Response to Oral Sucrose and Its Association with Recent Drinking
A preference for sweet tastes has been repeatedly shown to be associated with alcohol preference in both animals and humans. In this study, we tested the extent to which recent drinking is related to blood oxygen level–dependent (BOLD) activation from an intensely sweet solution in orbitofrontal areas known to respond to primary rewards.
Sixteen right-handed, non-treatment-seeking, healthy volunteers (mean age: 26 years; 75% male) were recruited from the community. All underwent a taste test using a range of sucrose concentrations, as well as functional magnetic resonance imaging (fMRI) during pseudorandom, event-driven stimulation with water and a 0.83 M concentration of sucrose in water.
[Sucrose > water] provoked a significant BOLD activation in primary gustatory cortex and amygdala, as well as in the right ventral striatum and in bilateral orbitofrontal cortex. Drinks/drinking day correlated significantly with the activation as extracted from the left orbital area (r = 0.52, p = 0.04 after correcting for a bilateral comparison). Using stepwise multiple regression, the addition of rated sucrose liking accounted for significantly more variance in drinks/drinking day than did left orbital activation alone (multiple R = 0.79, p = 0.002).
Both the orbitofrontal response to an intensely sweet taste and rated liking of that taste accounted for significant variance in drinking behavior. The brain response to sweet tastes may be an important phenotype of alcoholism risk.