Eating Disorder Diagnosis Moderates Pathological Exercise and White Matter Volume Relationship

679 

Abstract Submission 

Elana Kotler¹, Anastasia Haidar², Amanda Lyall², Ziyu Zhao³, Adrienne Romer⁴, Felicia Petterway³, Lauren Lindman³, Jason Scott⁴, Meghan Slattery³, Nour Shamseddine², Tara Kyaw³, Caroline Judson⁴, David Alperovitz⁴, Judith Halperin⁴, Kristin Javaras⁴, Esther Dechant⁴, Elizabeth Lawson³, Jennifer Thomas³, Marek Kubicki², Madhusmita Misra³, Kamryn Eddy³, Lauren Breithaupt⁵

¹Massachusetts General Hospital, Lynnfield, MA, ²Brigham and Women's Hospital, Boston, MA, ³Massachusetts General Hospital, Boston, MA, ⁴McLean Hospital, Belmont, MA, ⁵Harvard Medical School, Boston, MA

Elana Kotler  
Massachusetts General Hospital
Lynnfield, MA

Anastasia Haidar  
Brigham and Women's Hospital
Boston, MA

Amanda Lyall, PhD  
Brigham and Women's Hospital
Boston, MA

Ziyu Zhao  
Massachusetts General Hospital
Boston, MA

Adrienne Romer  
McLean Hospital
Belmont, MA

Felicia Petterway  
Massachusetts General Hospital
Boston, MA

Lauren Lindman  
Massachusetts General Hospital
Boston, MA

Jason Scott  
McLean Hospital
Belmont, MA

Meghan Slattery  
Massachusetts General Hospital
Boston, MA

Nour Shamseddine  
Brigham and Women's Hospital
Boston, MA

Tara Kyaw  
Massachusetts General Hospital
Boston, MA

Caroline Judson  
McLean Hospital
Belmont, MA

David Alperovitz, PsyD  
McLean Hospital
Belmont, MA

Judith Halperin, PsyD  
McLean Hospital
Belmont, MA

Kristin Javaras, PhD  
McLean Hospital
Belmont, MA

Esther Dechant, MD  
McLean Hospital
Belmont, MA

Elizabeth Lawson, MD  
Massachusetts General Hospital
Boston, MA

Jennifer Thomas, PhD  
Massachusetts General Hospital
Boston, MA

Marek Kubicki, MD, PhD  
Brigham and Women's Hospital
Boston, MA

Madhusmita Misra, MD, MPH  
Massachusetts General Hospital
Boston, MA

Kamryn Eddy, PhD  
Massachusetts General Hospital
Boston, MA

Lauren Breithaupt  
Harvard Medical School
Boston, MA

Both animal and human studies suggest that more frequent physical activity can promote brain health1. Observational studies consistently conclude that higher levels of physical activity are associated with global elevations of gray matter volume(GMV) and white matter volume(WMV). However, physical activity among individuals with restrictive eating disorders such as anorexia nervosa(AN) and atypical AN(At-AN) is a pathological component. While food restriction is the primary driver of weight loss in both AN and At-AN, pathological exercise compounds the effect of food restriction. Levels of pathological exercise are often similar between individuals with AN and At-AN, representing a symptom consistently associated with worse treatment outcomes4.
Recent literature has shown that individuals diagnosed with AN have reduced GMV/WMV in the brain, which is driven by severe low-weight status5. Based on these findings, we hypothesized that the number of pathological exercise hours would positively predict GMV/WMV in At-AN. However, due to the consistent GMV loss reported in AN that is driven by low-weight status, we predicted exercise hours would negatively predict GMV/WMV in AN.

This study utilized structural MRI data from 54 females(14-35y, avg = 22.6y). Consistent with the image-processing pipeline at the Psychiatry Neuroimaging Laboratory8, MRI images were axis-aligned, centered, and visually quality checked prior to a high-definition brain extraction tool9 to omit non-brain tissue. Automatically generated masks were processed through Freesurfer(v7.1.0) using the Desikan-Killiany atlas10.
Individuals were diagnosed with a current diagnosis of AN, AN in partial recovery(AN-prec), or At-AN based. In addition, individuals were characterized based on lifetime eating disorder history, classifying individuals into either lifetime AN or lifetime At-AN. Total exercise hours were defined by the number of hours spent exercising over the past 3 months.We investigated the within-group effect of exercise hours on GMV/WMV, between-diagnostic-group differences(AN, AN-prec, At-AN; lifetime AN, lifetime At-AN) in total GMV/WMV, and how diagnosis moderates the GMV/WMV-exercise relationship. Group differences between GMV, WMV, and exercise hours were assessed using linear mixed effect models while covarying for age, BMI z-scores, and head size. The relationship between GMV/WMV, exercise hours, and diagnostic group was evaluated using a linear model with diagnosis as the moderator.

We found that within-group effects of exercise hours on total GMV and WMV were absent, as were between-group (AN vs. AN-prec vs. At-AN; lifetime AN vs lifetime At-AN) effects on GMV/WMV. Our analysis showed that both current and lifetime diagnoses moderated the WMV and exercise hours relationship(current: ß = 601, t = 2.4, p = 0.02; lifetime: ß = 662, t = 2.8, p = 0.008). Individuals with current(Figure 1) and lifetime(Figure 2) At-AN who exercised for a greater number of hours demonstrated greater WMV. WMV in current AN, current AN-prec, and lifetime AN remained suppressed in the context of greater exercise hours, likely due to the diagnosis' low-weight requirement.

Our preliminary results suggest that exercise does not impact GMV in AN or At-AN. However, they do illustrate that exercise hours may positively impact WMV but only in the context of At-AN. Future research is necessary to distinguish both eating disorder groups from a healthy control group and whether specific types of exercise influence the WMV/GMV-exercise relationship. Prospective developments could include investigating weight trajectories to determine if there is a weight range at which exercise is beneficial for the brain.

Psychiatric (eg. Depression, Anxiety, Schizophrenia) ¹

Anatomical MRI ²

Eating Disorders

MRI

White Matter