Predicting PTSD with Hippocampus Connectivity

Meghan Bennett and Maria Cecilia Abreu-Gonzalez

August 22, 2022

Hippocampal resting-State Functional Connectivity Forecasts Individual PTSD Symptoms: A Data-Driven Approach

Key Points:
Individuals with posttraumatic stress disorder (PTSD) demonstrate altered hippocampal functional connectivity at rest (rsFC), and these alterations are associated with PTSD symptom severity.  
Data-driven approaches call for a shift in viewing PTSD as a disorder specific to only certain brain regions.
Early screening for risk of PTSD may be benefited by examining neurobiological features such as hippocampal rsFC.

Resting state connectivity is the expected signals between brain regions when a person is not engaged with any particular task(absence of stimulus). Individuals with PTSD have irregular resting state functional connectivity (rsFC) which correlates with PTSD symptom severity.Using a region-of-interest–based methodology, which looks at specific brain regions, previous small-scale research has shown that hippocampus rsFC assessed acutely after trauma is predictive of future symptom severity. Despite the fact that this is a promising biomarker, no study has employed a data-driven strategy to investigate whole-brain hippocampal FC patterns in predicting the onset of PTSD symptoms. The present study examines hippocampal rsFC at the whole-brain level rather than only limbic structures, which are brain structures crucial for behavioral and emotional responses. Ninety-eight adult survivors of traumatic injuries underwent an brain scan within 1 month of injury and again 6 months later. PTSD symptoms were assessed to examine whether whole-brain hippocampal rsFC predicts future symptom severity. Results revealed that hippocampus rsFC strongly predicted future PTSD severity even after adjusting for baseline PTSD symptoms, anxiety, and depression (commonly comorbid withPTSD). The findings indicate that research into the molecular bases of PTSD should not be limited to limbic structures. Given the role of the hippocampus in memory formation and fear regulation, these findings suggests incorporating whole-brain hippocampal activity into early screening could be beneficial to treatment prognosis and identification of those most at risk for developing PTSD. This is particularly relevant given that PTSD is often difficult to screen.

***Figure below depicts significant relationship between actual and predicted Clinician-Administered PTSD Scale for DSM-5(CAPS-5) scores based on the multivariate pattern analysis algorithm controlling for all covariates (B = 0.59,SE = 0.20, p = .003). rsFC, resting state functional connectivity.

Fitzgerald, J. M., Webb, E. K., Weis, C. N., Huggins, A. A., Bennett, K. P., Miskovich, T. A., Krukowski, J. L., deRoon-Cassini, T. A., & Larson, C. L. (2021). Hippocampal resting-state functional connectivity forecasts individual posttraumatic stress disorder symptoms: A data-driven approach. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, S2451902221002329.