The Acute Effects Of Moderate Intensity Exercise Vs Quiet Rest On State Anhedonia In MDD

Introduction: A cardinal symptom of Major Depressive Disorder (MDD) is persistent anhedonia (ANH) which significantly impairs motivation and engagement. Recent evidence suggests that aerobic exercise (AE) may improve ANH, with effects within the context of therapy unexplored. Purpose: To explore the acute effects of AE on ANH in adults with MDD within an intervention using AE to prime cognitive behavioral therapy (CBT). Methods: Adults (n = 40) diagnosed with DSM-5 MDD, were randomly assigned to complete 8-weekly sessions of 30-min of moderate-intensity AE (n = 19; rating of perceived exertion = 13) or quiet rest (n = 21; QR). Each session included the assigned condition immediately followed by a 50-min manualized CBT session. Self-reported state ANH was assessed before the condition (pre), immediately after the condition (post), and post-therapy via the Dimensional Anhedonia Rating Scale (DARS; with higher scores indicating less anhedonia) and ANH visual analog scale (VAS; 0 = No pleasure at all, 100 = Extreme pleasure). Scores from all 8 sessions were used. Changes in DARS and VAS by group were assessed through repeated measures 2 (condition) x 3 (time) ANOVA and pairwise comparisons. Cohen’s d was used to evaluate between-group differences. Results: For the DARS, there was a significant group by time interaction (p = 0.01). Within-group pairwise comparisons showed significantly higher DARS scores for AE at post (p < 0.01), but not for QR (p = 0.06; between group d = 0.43) and significantly higher scores at post-therapy for both conditions (p’s < 0.01) when compared to pre. For the VAS, there was a significant group by time interaction (p < 0.01). Within-group pairwise comparisons showed significant increases in VAS scores at post for AE (p < 0.01) and QR (p < .01; between group d = 0.44), and significant increases at post-therapy (p’s < 0.01) when compared to pre. Conclusion: The results suggest that AE acutely improved ANH when compared to QR, with benefits potentially persisting through a subsequent CBT session. This might indicate that priming CBT with structured, moderate intensity AE immediately beforehand may improve ANH, which may help to facilitate better engagement during a CBT session. Further exploring the psychobiological mechanisms underlying AE’s ANH effects and their impacts on outcomes of CBT is warranted.