Stress-induced alterations in HPA-axis reactivity and mesolimbic reward activation in individuals with emotional eating

Abstract

Background: Emotional eating has emerged as a contributing factor to overeating, potentially leading to obesity or disordered eating behaviors. However, the underlying biological mechanisms related to emotional eating remain unclear. The present study examined emotional, hormonal, and neural alterations elicited by an acute laboratory stressor in individuals with and without emotional eating.

Methods: Emotional (n = 13) and non-emotional eaters (n = 15) completed two main study visits, one week apart: one visit included a Stress version and the other a No-stress version of the Maastricht Acute Stress Task (MAST). Immediately pre- and post-MAST, blood was drawn for serum cortisol and participants rated their anxiety level. After the MAST, participants completed a Food Incentive Delay (FID) task during functional magnetic resonance imaging (fMRI), followed by an ad libitum snack period.

Results: Emotional eaters exhibited elevated anxiety (p = 0.037) and cortisol (p = 0.001) in response to the Stress MAST. There were no changes in anxiety or cortisol among non-emotional eaters in response to the Stress MAST or in either group in response to the No-stress MAST. In response to the Stress MAST, emotional eaters exhibited reduced activation during anticipation of food reward in mesolimbic reward regions (caudate: p = 0.014, nucleus accumbens: p = 0.022, putamen: p = 0.013), compared to non-emotional eaters. Groups did not differ in snack consumption.

Conclusions: These data indicate disrupted neuroendocrine and neural responsivity to psychosocial stress amongst otherwise-healthy emotional eaters, who demonstrated hyperactive HPA-axis response coupled with hypoactivation in reward circuitry. Differential responsivity to stress may represent a risk factor in the development of maladaptive eating behaviors.

Keywords: Cortisol; Eating behaviors; Emotional eating; Food reward; Stress; fMRI.

Figure 1.. Schematic depiction of the main visit protocol.

Fasting baseline (BL) blood draw for cortisol and anxiety ratings were collected around 8:30 am, followed by a 15-minute breakfast meal. Next, T0 cortisol and anxiety ratings were completed, after which the MAST (Maastricht Acute Stress Task; stress or no-stress version) was administered, followed by the fMRI (functional magnetic resonance imaging) scan and ad libitum snack period.

Figure 2.. Food Incentive Delay (FID) Task Design.

During the FID, each trial began with a cue indicating the participant would have the opportunity to earn a food reward (reward trials; denoted by a blue triangle) or not have the opportunity to earn a food reward (no incentive trials; denoted by a blue hexagon). Following a variable delay of 1-6 seconds, a target appeared (green circle) prompting the participant to press a button as quickly as possible (as previously trained during a practice trial). This was followed by another variable delay of 1-6 seconds, after which feedback was provided indicating whether the button press occurred within the time limit (success) or not (fail). Trials were separated by an intertrial interval of 1-6 seconds.

Figure 3.. Effect of Stress on Anxiety Ratings in Emotional and Non-Emotional Eaters.

Mean (±SEM) anxiety ratings before (T0) and after (T20) the Stress or No-stress control task for emotional eaters (EE) compared to non-emotional eaters (NE). *p<0.05, **p<0.01.

Figure 4.. Effect of Stress on Serum Cortisol in Emotional and Non-Emotional Eaters.

Mean (±SEM) serum cortisol levels before (T0) and after (T20) the Stress or No-stress control task for emotional eaters (EE) compared to non-emotional eaters (NE). **p<0.01.

Figure 5.. Relationship between Anxiety Ratings and Serum Cortisol in Response to Stress in Emotional and Non-Emotional Eaters.

Positive correlation between absolute change in self-reported anxiety [change in visual analogue scale (VAS) nervousness ratings from T0 to T20] and percentage change in cortisol (from T0 to T20) during the Stress visit.

Figure 6.. Effect of Stress on Activation during Food Reward Anticipation in Emotional and Non-Emotional Eaters.

Food reward-related anticipatory activation in emotional eaters (EE) and non-emotional eaters (NE) in response to stress vs. no-stress. Relative to the No-stress visit, during the Stress visit, the EE group exhibited significantly lower activation during anticipation of food reward in the (A) nucleus accumbens, (B) caudate, and (C) putamen. Coronal slices (left panel) showing anticipatory reward activity [Anticipation of food reward vs. Anticipation of neutral] in reward regions are shown for the interaction between Group and Visit. Parameter estimates extracted from each region (right panel). *p<0.05.

Figure 7.. Relationship between Anxiety Ratings and Activation during Food Reward Anticipation in Response to Stress in Emotional and Non-Emotional Eaters.

Negative correlation between absolute change in self-reported anxiety [change in visual analogue scale (VAS) nervousness ratings from T0 to T20] and brain activation during the food reward anticipation in (A) the nucleus accumbens (NAcc) and (B) caudate during the Stress visit.