Structural correlates of anhedonia across psychiatric diagnoses: a dimensional analysis

Anhedonia, the reduced capacity to experience or anticipate pleasure, is a transdiagnostic feature predicting poor outcome. Its structural correlates and whether the anticipatory and consummatory components have separable anatomy remain unclear. We analysed structural MRI and TEPS scores from 195 adults (85 healthy controls; 110 outpatients: MDD n = 37, anxiety n = 29, bipolar n = 18, psychotic-spectrum n = 12, other n = 14) in the openly available Transdiagnostic Connectome Project. Volumes of ten cortical and subcortical regions were extracted using the volBrain/AssemblyNet pipeline and adjusted for head size. After FDR correction, greater orbitofrontal (ρ = 0.247) and right medial prefrontal volume, and smaller lateral ventricular volume, were associated with greater pleasure capacity. These associations persisted after adjustment for depression severity (MADRS, DASS-D), anxiety severity, medication and diagnosis, but were attenuated and no longer significant after adjustment for age. Anticipatory and consummatory pleasure did not differ in their structural correlates. Orbitofrontal, right medial prefrontal and lateral ventricular volumes therefore covary with pleasure capacity across diagnoses, but the associations appear to reflect a shared age effect rather than an anhedonia-specific mechanism, and age-matched longitudinal studies will be needed.