Affect regulation and food intake in bulimia nervosa: Emotional responding to food cues after deprivation and subsequent eating

Startle as an objective measure of distress related to teasing and body image

OBJECTIVE

The startle reflex was used to assess negative emotion in response to body image cues in persons with and without body-related teasing histories.

METHOD

Fifty-three female college students viewed photos of themselves both unaltered and morphed to look heavier and thinner. Participants with a teasing history were compared to participants without a teasing history on self-report measures and the affect modulated startle paradigm when viewing the photos.

RESULTS

All participants, regardless of teasing history, self-reported that the photo morphed to look heaviest was more unpleasant than the neutral photo. When assessed by the affect modulated startle paradigm, a significant teasing history by photo interaction was found between the neutral and morphed to look heaviest photos and the neutral and morphed to look smallest photo. Those with a teasing history had greater startle response to the morphed images in comparison to the neutral images than did those without a teasing history.

DISCUSSION

College-aged women with weight-related teasing histories may have negative emotional reactions to personally relevant body image cues, as measured by the startle reflex, even when they subjectively report no distress. Objective measures, such as the startle reflex should be considered when assessing emotional reactions to body image cues.

Information processing of food pictures in binge eating disorder

Previous research has yielded evidence of attentional biases for food-related cues in binge eating disorder (BED) using behavioural measures such as the Stroop and dot probe paradigm. Being a more direct measure of attentional processing, the present study used event related potentials (ERPs) to test reactivity to high caloric and low caloric food pictures in women with BED compared to overweight healthy female controls (HC). In order to detect a possible motivational ambivalence, self-report and psychophysiological measures of the sympathetic and parasympathetic response system were assessed additionally. The main results yielded evidence that in women with BED high caloric food pictures elicit larger long latency ERPs compared to HC. By contrast, no such group difference was found for low caloric food pictures. Peripheral measures did not yield any group differences with respect to the processing of the caloric value of food. The results suggest that for women with BED, high caloric food may have high motivational properties and consume large parts of attentional resources. In the context of an environment in which high caloric food is omnipresent, such an abnormal processing may be relevant for the maintenance of the disorder.

Oral sensory and cephalic hormonal responses to fat and non-fat liquids in bulimia nervosa

Sensory evaluation of food involves endogenous opioid mechanisms. Bulimics typically limit their food choices to low-fat "safe foods" and intermittently lose control and binge on high-fat "risk foods". The aim of this study was to determine whether the oral sensory effects of a fat versus a non-fat milk product (i.e., traditional versus non-fat half-and-half) resulted in different subjective and hormonal responses in bulimic women (n=10) compared with healthy women (n=11). Naltrexone (50mg PO) or placebo was administered 1h before, and blood sampling began 30 min prior to and 29 min after, a 3 min portion controlled modified sham-feeding trial. Following an overnight fast, three morning trials (fat, naltrexone; fat, placebo; and non-fat, placebo) were administered in a random double-blind fashion separated by at least 3 days. Overall, there were no differences between Fat and Non-Fat trials. Hunger ratings (p<0.001) and pancreatic polypeptide levels (p<0.05) were higher for bulimics at baseline. Bulimics also had overall higher ratings for nausea (p<0.05), fatty taste (p<0.01), and fear of swallowing (p<0.005). Bulimics had approximately 40% higher total ghrelin levels at all time points (p<0.001). Hormones and glucose levels were not altered by the modified sham-feeding paradigm. Naltrexone, however, resulted in an overall increase in blood glucose and decrease in ghrelin levels in both groups (p<0.05, for both). These data suggest that bulimic women have different orosensory responses that are not influenced by opioid receptor antagonism, evident in hormonal responses, or dependent on the fat content of a similarly textured liquid.

Vagus nerve stimulation and emotional responses to food among depressed patients

BACKGROUND

Approved for treatment of treatment-resistant depression and for epilepsy, vagus nerve stimulation (VNS) therapy involves stimulation of the vagus nerve, affecting both mood and appetite regulating systems. VNS is associated with changes in food intake and weight loss in animals. Studies of its impact on food intake and weight with humans are limited. It is not known whether or how VNS influences emotional response to food, but vagus afferents project to regions in the insula involving satiety and taste.

METHOD

Thirty-three participants were recruited for three groups: depressed patients undergoing VNS therapy, depressed patients not undergoing VNS therapy, and healthy controls. All participants viewed images of foods twice in random order. When applicable, VNS devices were turned on for one viewing and off for the other. Participants were instructed to rate immediately after the viewings how each picture made them feel on a visual analog on three dimensions (unhappy to happy, calm to aroused, and small/submissive to big/domineering).

RESULTS

Controlling for time since last meal, a significant main effect was found for arousal ratings in response to sweet food images. Post-hoc analyses indicated that the VNS group demonstrated significant changes in arousal ratings between paired food image viewings compared to controls. Sixty-four percent of VNS participants demonstrated increases and 36% demonstrated decreases in arousal. Higher body mass indexes and greater levels of self-reported sweet cravings were associated with increased arousal during VNS activation.

CONCLUSIONS

This study was the first to examine the effects of acute left cervical VNS on emotional ratings of food in adults with major depression. Results suggest that VNS device activation may be associated with acute alteration in arousal response to sweet foods among depressed patients. Future research is needed to replicate these findings and to assess how activation of the vagus nerve affects eating and weight.