Excessive Avoidance Behaviors in Anorexia Nervosa: the Role of Reward

Study Overview
=================
Brief Summary
-----------------
This study investigates excessive avoidance behaviors in patients with a diagnosis of Anorexia Nervosa (AN) compared to a healthy control group. The study further examines the role of reward (relief) as a putative factor in maintaining excessive avoidance behaviors in AN.

Detailed Description
-----------------
Anorexia Nervosa (AN) is a life-threatening mental disease with a disappointing treatment outcome. Fear of weight gain and diet restrictions are considered the core symptoms of AN. Although from a diagnostic perspective AN is conceptualized as an eating-related disorder connected to an extremely low Body Mass Index (BMI) and body image distortion, AN might represent a specific phenotype of anxiety disorders characterized by tenacious avoidance behaviors, especially the restrictive subtype. To date, avoidance in AN is often investigated as a general personality trait (e.g. harm avoidance) but poorly examined in its behavioral form (which is life-threatening, such as food-avoidance). Hence, the investigators will perform a systematic investigation of excessive avoidance behaviors within a laboratory setting. Within a learning perspective, the investigators will investigate excessive avoidance in a group of 30 AN patients and 30 healthy volunteers. To achieve this, a well-validated avoidance paradigm will be used. Most critically, the investigators will examine whether patients with a diagnosis of anorexia nervosa show persistent avoidance behaviors compared to a control group. Additionally, the investigators will examine if, in the anorexia group, higher subjective relief to successful omissions of negative events during avoidance learning predicts persistent (excessive) avoidance behaviors after fear extinction.

Official Title
-----------------
Excessive Avoidance Behaviors in Anorexia Nervosa: the Role of Reward

Conditions
-----------------
Eating Disorders, Anxiety, Anorexia Nervosa

Intervention / Treatment
-----------------
* Behavioral: Behavioral avoidance task


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: For the AN group, patients need to be physically strong and sufficiently emotionally stable For the healthy group, the investigators will recruit participants without a previous or current history of psychiatric, cardiovascular, neurological or other relevant disorder Exclusion Criteria: For the AN group, the investigators will exclude patients who are insufficiently emotionally stable and/or physically weak to participate in the study as estimated by the treating physicians of the units on which the patients are admitted Insufficient verbal skills to understand the questionnaires and the computer task Participants who are pregnant or breastfeeding

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Healthy controls<br>The healthy control group will perform a well-validated avoidance (behavioral) task and will fill in some questionnaires about eating behaviors, emotions, and feelings. | Behavioral: Behavioral avoidance task<br>* Behavioral task able to measure avoidance actions, US-expectancy, and reward-related indexes in different learning times<br>|
| Anorexia Nervosa patients<br>As the healthy controls, the participants of the anorexia nervosa group will perform the same behavioral task and will fill in the same questionnaires | Behavioral: Behavioral avoidance task<br>* Behavioral task able to measure avoidance actions, US-expectancy, and reward-related indexes in different learning times<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Button clicks during a red cue will be recorded as a measure of avoidance (binary response) | To investigate whether, compared to healthy controls, individuals with a diagnosis of anorexia nervosa show excessive avoidance behaviors (frequent clicking to prevent the aversive stimulus). Repeated measure ANOVA (analysis of variance) will be employed to evaluate differences between groups. If data will violate the assumption of normality, mixed or generalize methods will be used. | through study completion, an average of 1 year | 
| Relief pleasantness ratings (Visual Analog Scale, from neutral [0] to very pleasant [100]) | To investigate whether, compared to healthy controls, individuals with a diagnosis of anorexia nervosa show higher relief pleasantness during the omission of the aversive stimuli. The investigators will also test if such responses predict a return in avoidance behaviors (button click) after fear has been extinguished. Repeated measure ANOVA (analysis of variance) and multiple linear regressions will be employed to evaluate differences between groups. If data will violate the assumption of normality mixed or generalize methods will be used. | through study completion, an average of 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| US-Expectancy ratings (Likert scale from 0:no picture to 10:certainly a picture) | To investigate whether, compared to healthy controls, individuals with a diagnosis of anorexia nervosa show higher US-expectancies during both avoidance learning and fear extinction learning. Repeated measure ANOVA (analysis of variance) will be employed to evaluate differences between groups. If data will violate the assumption of normality mixed or generalize methods will be used. | through study completion, an average of 1 year | 
| Eating Disorders Inventory [EDI] | Higher scores at the EDI, and especially to the drive for thinness subscale, correlate with higher avoidance actions. | through study completion, an average of 1 year | 
| Distress Tolerance Scale [DTS] | Lower scores at the DTS correlate with higher relief and higher avoidance actions | through study completion, an average of 1 year |