Intact value-based decision-making during intertemporal choice in women with remitted anorexia nervosa? An fMRI study

Abstract

Background: Extreme restrictive food choice in anorexia nervosa is thought to reflect excessive self-control and/or abnormal reward sensitivity. Studies using intertemporal choice paradigms have suggested an increased capacity to delay reward in anorexia nervosa, and this may explain an unusual ability to resist immediate temptation and override hunger in the long-term pursuit of thinness. It remains unclear, however, whether altered delay discounting in anorexia nervosa constitutes a state effect of acute illness or a trait marker observable after recovery.

Methods: We repeated the analysis from our previous fMRI investigation of intertemporal choice in acutely underweight patients with anorexia nervosa in a sample of weight-recovered women with anorexia nervosa (n = 36) and age-matched healthy controls (n = 36) who participated in the same study protocol. Follow-up analyses explored functional connectivity separately in both the weight-recovered/healthy controls sample and the acute/healthy controls sample.

Results: In contrast to our previous findings in acutely underweight patients with anorexia nervosa, we found no differences between weight-recovered patients with anorexia nervosa and healthy controls at either behavioural or neural levels. New analysis of data from the acute/healthy controls sample sample revealed increased coupling between dorsal anterior cingulate cortex and posterior brain regions as a function of decision difficulty, supporting the hypothesis of altered neural efficiency in the underweight state.

Limitations: This was a cross-sectional study, and the results may be task-specific.

Conclusion: Although our results underlined previous demonstrations of divergent temporal reward discounting in acutely underweight patients with anorexia nervosa, we found no evidence of alteration in patients with weight-recovered anorexia nervosa. Together, these findings suggest that impaired valuebased decision-making may not constitute a defining trait variable or “scar” of the disorder.

Fig. 1

Intertemporal choice task. Each of the 90 trials of the main task performed during functional MRI began with the presentation of the larger later (LL) amount and the respective delay (2 s), followed by a fixation period (6 s) and a response window (2 s). During the response window, an exclamation mark presented on the left or right side of the screen indicated which button was mapped to the LL amount for that trial. Decisions for the delayed reward (LL) were mapped to the right button in half of the trials and the left button in the other half. Each trial ended with feedback confirming the decision, followed by a jittered interval with an average duration of 7 s.

Fig. 2

Main behavioural results. (A) Logarithmized and z-standardized k values estimated from choice behaviour during the prescan calibration session for patients with weight-recovered anorexia nervosa (recovered) and healthy controls. (B) Rank-transformed and z-standardized area under the curve (AUC) values estimated from choice behaviour during the main task for the recovered and control groups.

Fig. 3

Activation of the dorsal anterior cingulate cortex (dACC) during difficult decisions. (A) Regions of the dACC showing greater activation as a function of decision difficulty (hard > easy) in the weight-recovered anorexia nervosa/healthy control sample from the current analyses (red region; main effect of decision difficulty; x = 6, y = 20, z = 46; t = 3.63; 321 voxels), and decreased hard v. easy activation in patients with acute anorexia nervosa relative to healthy controls from our previous analyses (yellow region; group × decision difficulty interaction; x = −10, y = 30, z = 28; t = 3.58; 580 voxels). Findings are shown at a voxel-wise threshold of p < 0.005 to illustrate their overlap (orange region; 92 voxels; p_FWE,SVC < 0.05). No other significant main effects or interactions were evident in the recovered/control or acute/control comparisons at this statistical threshold. (B) Mean dACC activation for the recovered and healthy control groups on trials with hard and easy decisions (β estimates ± standard error of the mean). A group × difficulty repeated-measures analysis of variance of the β estimates confirmed that while activation was increased in this region for hard v. easy trials (F_1,70 = 11.0; p < 0.001), group activation levels did not generally differ (F_1,70 = 0.006; p = NS), and no interaction was evident (F_1,70 = 0.023; p = NS). For qualitative comparisons with the acute sample, age-adjusted dACC activation is shown for all study participants in Appendix 1, Fig. S3. FWE = family-wise error; NS = not significant; SVC = small-volume corrected.

Fig. 4

Altered functional connectivity of the dorsal anterior cingulate cortex (dACC) during difficult decisions in patients with acute anorexia nervosa. Results p_FWE < 0.05, t map) of a generalized psychophysiological interaction analysis of dACC connectivity as a function of decision difficulty (hard > easy) indicating greater coupling with a broad region of the inferior parietal lobule and somatosensory cortex in patients with acute anorexia nervosa relative to healthy controls, as determined by a new analysis of the data originally analyzed in King and colleagues. Note that no group differences in dACC functional connectivity were detected in an analogue analysis of the data from the weight-recovered anorexia-nervosa/healthy control sample at the focus of the current article. FWE = family-wise error.