Individual differences in nucleus accumbens activity to food and sexual images predict weight gain and sexual behavior

Abstract

Failures of self-regulation are common, leading to many of the most vexing problems facing contemporary society, from overeating and obesity to impulsive sexual behavior and STDs. One reason that people may be prone to engaging in unwanted behaviors is heightened sensitivity to cues related to those behaviors; people may overeat because of hyperresponsiveness to food cues, addicts may relapse following exposure to their drug of choice, and some people might engage in impulsive sexual activity because they are easily aroused by erotic stimuli. An open question is the extent to which individual differences in neural cue reactivity relate to actual behavioral outcomes. Here we show that individual differences in human reward-related brain activity in the nucleus accumbens to food and sexual images predict subsequent weight gain and sexual activity 6 months later. These findings suggest that heightened reward responsivity in the brain to food and sexual cues is associated with indulgence in overeating and sexual activity, respectively, and provide evidence for a common neural mechanism associated with appetitive behaviors.

Figures

Figure 1.

Representation of the cue-reactivity paradigm. Eighty images of each category [animals, food, sexual scenes, environmental scenes, general people, and people drinking alcohol (not shown)] were displayed one at a time for 2 s, followed by a brief (500 ms) fixation crosshair. Images were presented in a pseudorandom order and intermixed with jittered periods of fixation (crosshair) baseline.

Figure 2.

Nucleus accumbens activity to food and sexual images predicts weight gain and sexual desire, respectively. A, The anatomical ROI of the left NAcc with central Talairach coordinates (x, y, z) −9, 6, −4 is displayed on a coronal brain slice. B, Signal change in the left NAcc (anatomically defined ROI) in response to viewing food images at Time 1 positively correlated with change in BMI 6 months later (Time 2 − Time 1) (r = 0.37, p < 0.05). C, Signal change in the left NAcc ROI in response to viewing sexual scenes at Time 1 positively correlated with dyadic sexual desire (r = 0.39, p < 0.01). A similar correlation was observed between NAcc activity to sexual scenes and solitary sexual desire (data not shown; r = 0.36, p = 0.01).