Anhedonia is defined as the inability to experience positive emotional responses to positive stimuli, and is common in individuals exposed to traumatic events. As a distinct dimensional component of PTSD symptoms defined by DSM-5, anhedonia is connected with various prognoses such as PTSD chronicity, higher suicidality, greater impairment of social functioning and worse response to psychotherapy. However, less is known about the neural correlates of posttraumatic anhedonia symptoms.
A research team led by Prof. WANG Li from the Institute of Psychology, the Chinese Academy of Sciences (IP, CAS) discovered the significant decline of the resting-state functional connectivity (rsFC) between left ventral pallidum and various hub of default mode network (bilateral posterior cingulate cortex and precuneus Cortex) in the high posttraumatic anhedonia group, after controlling for sex, age and other posttraumatic stress symptoms, which reveal the neural connections of posttraumatic anhedonia symptoms.
The study included 88 adult earthquake survivors recruited from communities in Hanwang County in Sichuan, China. Participants were divided into low and high anhedonia groups based on the median score of the anhedonia subscale of the PCL. To contrast the functional connectivity between the two groups, whole brain seed-to-voxel analyses were executed, controlling for age, sex and severity of other PTSD symptoms. Nucleus accumbens and ventral pallidum in both hemispheres were selected as seed regions for the whole-brain analysis. As ventral pallidum has no available human anatomical mask, functional masks of ventral pallidum were created based on the reference coordinate of ventral pallidum in reward task fMRI human studies. The results were verified in the repeated analysis using the anatomical mask for the whole pallidum.
The present study is the first neuroimaging study to provide evidence for the association between the ventral pallidum and posttraumatic psychopathology symptoms. The findings provide empirical evidence for the hypothesis that diminished integration between reward regions and the default mode network may imply a cross-diagnostic intermediate phenotype corresponding to damage in reward-oriented internal cognition.
The study has been published in the Journal of Psychiatric Research on May 27, 2021.
Institute of Psychology
Chinese Academy of Sciences
Beijing 100101, China.