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.