(PS3-3) Assessing the Impact of Motivational Deficits on Physical Activity Levels in Individuals with Anhedonia

Anhedonia is the diminished ability to experience joy or pleasure and is considered a hallmark symptom of depressive disorders. Reward deficits are a core feature of anhedonia as disruptions in reward processes can lead to reduced capacity to experience pleasure and motivation. Physical activity is also associated with depressive symptoms; high levels of depressive symptoms have been shown to predict lower levels of physical activity, and vice versa. However, the mechanisms underlying this relationship are unclear and have not been comprehensively explored. 

Given that anhedonia is characterized by motivational deficits and that motivation is crucial for goal attainment and maintenance of health behaviors, we predicted that motivation may drive the association between anhedonia and reduced physical activity. Using baseline data (n = 47) from a randomized treatment study that evaluated the efficacy of a novel psychotherapy intervention for individuals with severe symptoms of anxiety or depression, we aimed to assess whether anhedonia cross-sectionally predicted motivational deficits and physical activity, and whether motivational deficits cross-sectionally predicted physical activity. Our primary outcomes were assessed using the Dimensional Anhedonia Rating Scale (DARS), the Effort Expenditure for Rewards Task (EEfRT), and Actigraphy. We hypothesized that higher levels of anhedonia would significantly predict greater motivational deficits as well as lower levels of physical activity. We also hypothesized that higher motivational deficits would significantly predict lower levels of physical activity. 

Regression analyses showed that anhedonia did not significantly predict motivational deficits (p = 0.69) or physical activity (p = 0.93), and that motivational deficits did not significantly predict levels of physical activity (p = 0.64). These findings suggest that other factors that were not accounted for in this study may influence the relationship between anhedonia and physical activity. Additionally, given our small sample size and use of cross-sectional data, it is possible that power to detect significant and causal effects was limited. Future research should examine the relationships between motivation, anhedonia, and physical activity longitudinally in a larger sample to better understand these associations and potential changes over time. Future findings could be consequential in addressing depressive symptoms and promoting healthy behaviors in individuals with anhedonia