Food induced distractibility in restrictive anorexia nervosa: Different motor patterns for different foods as revealed by a mouse tracker evaluation

Eyes on the body: Assessing attentional bias toward body-related stimuli in Anorexia Nervosa

OBJECTIVE

The aim of the present study was to assess whether patients with Anorexia Nervosa (AN) presented an attentional bias toward pictures of other women's bodies, as this bias could implicitly promote self-other comparisons thus increasing body/weight concerns.

METHODS

The sample included 48 healthy controls (HC) and 54 patients with AN. All participants performed a dot-probe task with pictures of bodies or body parts of underweight (UWB), normal weight (NWB) and overweight (OWB) women, while their gaze was recorded with an eye-tracking system. Two indices of attentional bias, a gaze direction bias and a gaze duration bias were extracted.

RESULTS

The models conducted on both direction bias and duration bias showed a significant main effect of group, revealing a stronger attentional bias toward bodies in patients as compared to controls. One sample t-tests conducted on the direction bias of patients with AN revealed that they presented a significant positive bias at 500 ms toward all the bodies. At 1500 ms, instead, they presented a positive bias toward UWB and an avoidance bias of OWB. HC instead presented an initial avoidance of all body stimuli, and an avoidance of NWB and OWB at 1500 ms.

DISCUSSION

Our results revealed a stronger attentional bias toward other women's bodies in patients than in HC. Moreover, patients presented a tendency to focalize their attention on UWB while they avoided maintaining their attention on OWB. This pattern might promote upward social comparisons, which are usually associated with negative self-evaluation and increased levels of body dissatisfaction.

Revealing motor insensitivity to food in Anorexia Nervosa as a potential mechanism contributing to calorie restriction: A mobile Approach Avoidance Task study

A change in implicit behavioural tendencies toward foods may contribute to the maintenance of calorie restriction in Anorexia Nervosa (AN). To test this hypothesis, we assessed approach-avoidance tendencies toward different categories of stimuli using a novel mobile version of the approach-avoidance task (AAT). The sample included 66 patients with restrictive AN and 84 healthy controls, all females. All participants performed the AAT in which they were required to approach or avoid stimuli (high-calorie foods, low-calorie foods, and neutral objects) by respectively pulling their phone towards themselves of pushing it away. Both the response time and the force of each movement were collected by means of the smartphone's accelerometer. The results revealed that patients with AN had a reduced tendency to approach food stimuli compared to healthy controls, who instead presented faster and stronger movements in approaching rather than avoiding foods as compared to neutral objects. This finding was particularly pronounced in patients with greater levels of malnutrition. No differences were instead observed comparing high-calorie and low-calorie foods. The observed reduction in the natural tendency to approach food stimuli is consistent with patients' eating behaviour and may contribute to the maintenance of calorie restriction, thus representing a possible target for novel therapeutic approaches.

Dissecting implicit food-related behaviors in Binge Eating Disorder and obesity: insights from a mobile approach-avoidance framework

Introduction

Bulimic episodes experienced by patients with Binge Eating Disorder (BED) might be sustained by an enhanced behavioral propensity to approach food stimuli.

Methods

To test this hypothesis, automatic approach avoidance tendencies toward high-calorie foods (HCF), low-calorie foods (LCF), and neutral objects were assessed in a group of 23 patients with BED, and their performance was compared to the one of 17 patients with obesity without BED and a group of 32 normal weight participants. All participants performed a mobile approach-avoidance task in which they were required to approach and avoid different stimuli by respectively pulling their phone toward themselves or pushing it away. Reaction times were analyzed.

Results

Results showed a significant three-way interaction between group, type of movement and stimulus. Post-hoc analyses revealed that all the groups displayed an approach bias toward HCF. Patients with BED and healthy controls also displayed an approach bias toward LCF, a bias that was absent in obese individuals without BED. Moreover, patients with BED were faster in approaching food stimuli, both HCF and LCF, compared to healthy controls.

Discussion

These behavioral tendencies are quite consistent with the real-life attitudes of both BED patients and patients with obesity and might contribute to the maintenance of unhealthy eating habits such as binging in patients with BED and high-calorie diets in patients with obesity.

Persistent avoidance of virtual food in anorexia nervosa-restrictive type: Results from motion tracking in a virtual stopping task

OBJECTIVE

Food avoidance is central to patients with anorexia nervosa-restrictive type (AN-R). Competing accounts in experimental psychopathology research suggest that food avoidance may result from automatic, habitual responses or from elevated inhibitory control abilities. This study investigated behavioral trajectories of food avoidance in a novel virtual reality stopping task.

METHOD

Sixty patients with AN-R and 29 healthy controls with normal weight were investigated using a novel, kinematic task in virtual reality. We recorded spatial displacement in stop- and go-trials to virtual food and control objects. Inhibitory control abilities were operationalized by the VR task in stopping performance (i.e., interrupted movement in stop-trials), whereas we also measured habitual avoidance of virtual food across both go- and stop-trials (i.e., delayed movement relative to nonfood objects).

RESULTS

In patients with AN-R, hand displacements were shorter to food versus nonfood across stop- and go-trials, reflected in a Stimulus × Group interaction. Healthy controls showed no differences. Importantly, the food-specific effect in AN-R was identical across stop- and go-trials, indicating habitual food avoidance. Moreover, stop error rates (i.e., stop-trials with response) were lower in patients with AN-R.

DISCUSSION

The findings suggest food-specific habitual avoidance and heightened generalized inhibitory control in AN-R. The continuously delayed displacements during active hand movements across stop- and go-trials indicated the persistence of patients' avoidance of food.

PUBLIC SIGNIFICANCE

Experimental research investigates the mechanisms underlying mental disorders such as anorexia nervosa. In this study, we measured interrupted hand movements in response to food pictures or neutral pictures (shoes) in patients with anorexia nervosa and healthy controls. A virtual reality scenario was used. Findings indicated that patients were slower at approaching food, interrupted or not. Key mechanisms of food avoidance can be translated into habit-based treatment options in future research.