Mapping links between real-world diversity, positive emotion, and neural dynamics in anhedonia

PROJECT SUMMARY Reduced positive affect is a core symptom of many stress-related psychiatric disorders, including depression and PTSD. Critically, positive affect is not simply the inverse of negative affect, and clinicians struggle to increase positive affect: Antidepressant and psychotherapeutic interventions often reduce depressed mood but are ineffective at increasing positive affect. And yet, qualitative studies of patients themselves indicate that a ‘full recovery’ requires increasing positive emotion, even when other depressive symptoms have subsided. Despite the critical role of positive emotion, very limited work has identified effective interventions to increase real-world positive affect to improve mental health. Guided by preclinical work, we recently discovered that positive affect is increased when going to a greater number of varied locations (“experiential diversity”). Moreover, the association between experiential diversity and positive affect appears to be supported specifically by functional connectivity between the hippocampus and nucleus accumbens–a stress susceptible circuit responsible for assigning reward value to novelty. This finding suggests that increasing experiential diversity may be a plausible real-world intervention to increase positive affect by strengthening specific neural circuits. Leveraging a strong team with complimentary expertise in mobile tracking, resting state fMRI, treatment development, and affective science, this R01 application will expand these initial findings in a large, demographically representative sample encompassing a range of anhedonia severity (from asymptomatic to severe) collecting geolocation (GPS), experience sampling of emotion, and functional MRI to, (1) precisely delineate the specific geospatial features of experiential diversity most strongly linked to increases in momentary (EMA measured) positive affect (e.g., neighborhoods one has never visited, green spaces, beach/ocean); (2) determine whether individuals with higher levels of anhedonia have similar affective benefits from these types of experiential diversity as individuals with lower experiential diversity; (3) determine the neural network circuit mechanisms supporting associations between experiential diversity and affect as a function of anhedonia; and (4) in an independent sample, experimentally induce experiential diversity to determine if it causes increased positive affect. Results from this application will help to define the neural mechanisms by which exploration and experiential diversity predict increases in positive affect and will yield actionable real-world interventions for a clinical trial to improve positive affect in those with heightened anhedonia.