Response to Acute Exercise in Eating Disorders

Individuals with eating disorders (ED) represent a high-priority clinical population, with among the highest mortality rates of any psychiatric disorder, and driven exercise (DEx) is a symptom evidenced in up to 80% of those with EDs that increases impairment and negatively impacts treatment outcome. This study will develop tasks to characterize cognitive, affective, and biological response to exercise among adolescent and young adult females with EDs and determine whether acute exercise response associates with free-living activity and DEx. This R21 project will provide foundational data to guide research and development of treatments that are more precisely targeted to the symptom of driven exercise and to ultimately improve clinical outcomes associated with EDs.

Eating disorders (EDs) are among the deadliest of all psychiatric disorders. However, first-line treatments for EDs are effective for only roughly 40% of adolescent patients. One barrier to treatment efficacy is the persistence of driven exercise (DEx; exercising in a compulsive manner to control weight and/or regulate emotion), a hallmark symptom reported among many adolescents diagnosed with restrictive EDs (59-73%). Among other negative sequelae, DEx is associated with suicidal behavior, poorer treatment outcome, increased comorbid psychopathology, and risk for relapse. Further, while multiple eating-related tasks have been validated that discriminate between individuals with EDs and healthy populations, there are currently no well-validated tasks that directly assess sensitivity and responsivity to exercise in ED populations. As DEx is a poorly understood symptom that plays a key role in ED maintenance, investigating its biobehavioral underpinnings is of critical importance. Existing research points towards both reward and threat functions of exercise, which may drive and perpetuate DEx among those with EDs. Evaluation of both reward and threat functions of exercise among those with EDs will improve mechanistic understanding of this ED feature; ultimately, improved understanding of DEx will inform treatment targets. The proposed project will recruit adolescent and young adult females (16-25y) with (n = 67) and without (n = 33) EDs from two sites to participate in a comprehensive evaluation of acute exercise response. The current project will 1) characterize variability in biobehavioral response to in-lab exposure to moderate-intensity exercise among those with and without EDs; 2) create and refine tasks that capture engagement of reward- and threat-related systems during exercise; and 3) test hypotheses that acute exercise response is more pronounced among individuals with EDs and that acute exercise response relates to ED symptom severity, DEx, and free-living activity. Detailed explication of acute exercise effects among individuals with EDs in a controlled setting will have significant impact on the empirical study of EDs, specifically to (i) improve assessment of DEx risk and function (ii) elucidate a testable model of DEx risk and (iii) suggest targets for DEx intervention. The methods validated in this project will improve understanding of DEx, a treatment- resistant ED feature. These methods will also lay the groundwork for larger-scale, clinical research which clarifies optimal targets for DEx in ED treatment.

Eligibility Criteria:
Inclusion Criteria:

* Aged 16-25
* ED participants must meet full criteria for DSM-5 restrictive-spectrum eating disorders characterized by weight and shape concern, I.e., anorexia nervosa (AN); mild, moderate, or in partial remission), atypical AN, and OSFED -AN type only)
* ED participants must be medically stable, and suitable for outpatient treatment
* Biological Females, Assigned Female at birth
* English Speaking

Exclusion Criteria:

* Those with a medical condition that precludes exercise (e.g., severe asthma) will be excluded for any contraindications

  * Biological Males, Assigned Male at birth
  * BMI less than 16 (over 18 years) or less than 75% expected body weight (under 18 years)
  * Reported intake on Eating Disorder Examination \<1000kcal daily
  * Current purging \>1x per day
  * Current regular episodes of objective binge eating (\>1x/wk)
  * Current self-report of loss-of control eating per the Eating Disorders Examination Interview
  * ED related hospitalization, partial hospitalization, or residential treatment in the past month
  * Any endorsed medical concerns related to physical activity (as probed in the phone screening questions regarding cardiovascular, pulmonary, or metabolic disease).
  * Major medical disorders (e.g., cancer, AIDS)
  * Physical discomfort or difficulty with blood draws
  * Psychotic disorders
  * Intellectual disabilities
  * Developmental disorders
  * Active substance use disorder
  * Current suicidal risk per the Ask Suicide Screening Questionnaire
  * Pregnancy
  * Psychiatric medications that have not been stable for at least 4 weeks
  * Acute sedatives / pain killers (e.g., benzodiazepines, opioids) and prescription stimulants (e.g., methylphenidate, amphetamines) are not permitted for the full day prior to the laboratory session. The noted short-term medication holds only apply to subjects taking the noted medications in cases used to treat ADHD or other psychiatric conditions
  * Resting heart rate \<50 beats per minute (assessed at screening visit)
  * Low blood pressure (\<90/60), (assessed at screening visit)
  * Daily cannabis use
  * History of light headedness or fainting during blood draws or physical activity
  * History of chest pain during physical activity
  * Bone, joint, cardiac, pulmonary, metabolic, or other medical conditions that may be worsened by physical activity (e.g., COPD, diabetes, hypertension) that are not currently addressed via medication or lifestyle change.
  * Physical disabilities that prohibit task performance (such as blindness or deafness)
  * Any other condition that the investigator believes might put the participant at risk for negative outcomes
  * Individuals with a restrictive eating disorder presentation that does not include weight and shape concern (ARFID) or that has primary binge eating (bulimia nervosa)
  * Indication of health risk associated with exercise on the Physical Activity Readiness Questionnaire