Poster A104, Saturday, March 24, 1:30–3:30 pm, Exhibit Hall C
Anterior insula-nucleus accumbens connectivity in PTSD: clinical and decision-making correlates
Elizabeth Olson1,2, Gwenievere Birster1, Scott Rauch1,2, Isabelle Rosso1,2; 1McLean Hospital, 2Harvard Medical School
Introduction: Hyper-responsivity of fear- and extinction-related regions including the anterior insula (AI) in PTSD is well-documented. Dysregulation in reward-related circuitry in PTSD has received increasing attention, including reduced activity in the nucleus accumbens (NAcc). Recently, a white matter pathway connecting the right AI to the right NAcc was identified in the human brain; this pathway likely involves inhibitory control of the right AI over NAcc activity. We hypothesized that increased right AI-NAcc coherence would be associated with greater symptom severity in PTSD. Methods: 20 participants (13 female) with current DSM-IV PTSD were included. Probabilistic tractography was performed using FSL’s bedpostx and probtrackx, from a seed in the right NAcc to the right AI. Tracts were masked and used to extract fractional anisotropy (FA) values. Age and gender were included as nuisance covariates. Results: Higher FA was associated with higher lifetime PTSD severity (CAPS scores, partial r (16) = 0.542, p = 0.020), driven by significant associations with avoidance and re-experiencing (but not hyperarousal) symptom clusters. In 11 participants who also had delay discounting data, higher FA was associated with steeper delay discounting, r (9) = -0.635, p = 0.036, but not with anhedonia, r (16) = 0.084. Conclusion: Increased FA between the right AI and right NAcc was associated with greater lifetime symptom severity. While hyperactivity in the AI and hypoactivity in the NAcc have been previously demonstrated, this finding suggests that altered white matter microstructure in the pathway connecting these regions may also be relevant to PTSD severity.
Topic Area: THINKING: Decision making