Attentional bias to food images associated with elevated weight and future weight gain: an fMRI study

Abstract

Behavioral studies reveal that obese vs. lean individuals show attentional bias to food stimuli. Yet research has not investigated this relation using objective brain imaging or tested whether attentional bias to food stimuli predicts future weight gain, which are important aims given the prominence of food cues in the environment. We used functional magnetic resonance imaging (fMRI) to examine attentional bias in 35 adolescent girls ranging from lean to obese using an attention network task involving food and neutral stimuli. BMI correlated positively with speed of behavioral response to both appetizing food stimuli and unappetizing food stimuli, but not to neutral stimuli. BMI correlated positively with activation in brain regions related to attention and food reward, including the anterior insula/frontal operculum, lateral orbitofrontal cortex (OFC), ventrolateral prefrontal cortex (vlPFC), and superior parietal lobe, during initial orientation to food cues. BMI also correlated with greater activation in the anterior insula/frontal operculum during reallocation of attention to appetizing food images and with weaker activation in the medial OFC and ventral pallidum during reallocation of attention to unappetizing food images. Greater lateral OFC activation during initial orientation to appetizing food cues predicted future increases in BMI. Results indicate that overweight is related to greater attentional bias to food cues and that youth who show elevated reward circuitry responsivity during food cue exposure are at increased risk for weight gain.

Figure 1

Time course of events during the food attention network test (ANT) to (a) time course of events to measure initial orientation to food images with appetizing food images appearing after a single green arrow contrasted to appetizing food images appearing after a double green arrow; and (b) time course of events to measure reallocation of attention to food images with unappetizing food images appearing on the opposite side of the single red arrow contrasted to unappetizing food images appearing on the concurrent side of the single red arrow.

Figure 2

Greater activation in (a) the anterior insula/frontal operculum (MNI coordinates: 36, 21, 6, Z =3.42, pFDR = 0.02) during orientation to appetizing food and (b) the ventrolateral prefrontal cortex (MNI coordinates: 39, 39, −3, Z = 3.24, pFDR = 0.03) during orientation to unappetizing food cues as a function of BMI. The effects remain significant at the pFDR = 0.05 level when data from the participant with the greatest BMI were excluded. Decreased activation in (c) orbitofrontal cortex (MNI coordinates: −24, 27, −12, Z = 3.13, pFDR = 0.04) and (d) ventral pallidum (MNI coordinates: 18, −6, 0, Z = 3.45, pFDR = 0.04) in response to reallocation of attention to unappetizing food images as a function of BMI.

Figure 3

Activation in the OFC (MNI coordinates: −39, 30, −12, Z = 3.24, pFDR = 0.05) in response to orientation to appetizing food cues was related to future increases in BMI. The effect remained significant when the participant with the greatest increase in BMI was excluded.