Automated measurement of hippocampal subfields in PTSD: Evidence for smaller dentate gyrus volume

Abstract

Smaller hippocampal volume has been consistently observed as a biomarker of posttraumatic stress disorder (PTSD). However, less is known about individual volumes of the subfields composing the hippocampus such as the dentate gyrus and cornu ammonis (CA) fields 1-4 in PTSD. The aim of the present study was to examine the hypothesis that volume of the dentate gyrus, a region putatively involved in distinctive encoding of similar events, is smaller in individuals with PTSD versus trauma-exposed controls. Ninety-seven recent war veterans underwent structural imaging on a 3T scanner and were assessed for PTSD using the Clinician-Administered PTSD Scale. The hippocampal subfield automated segmentation program available through FreeSurfer was used to segment the CA4/dentate gyrus, CA1, CA2/3, presubiculum, and subiculum of the hippocampus. Results showed that CA4/dentate gyrus subfield volume was significantly smaller in veterans with PTSD and scaled inversely with PTSD symptom severity. These results support the view that dentate gyrus abnormalities are associated with symptoms of PTSD, although additional evidence is necessary to determine whether these abnormalities underlie fear generalization and other memory alterations in PTSD.

Smaller hippocampal CA1 subfield volume in posttraumatic stress disorder

“…An estimation of statistical power for the largest published study (n=97) [7] to detect group differences in CA1 volume based on the effect size we observed (Cohen’s d=.21), reveals only 55.3% power to reject the null hypothesis or a 44.7% chance of a false positive. By comparison, the present sample size (n=282) based on the same effects size (0.21) attains 94.9% power to reject the null or a 5.1% chance of a false positive.…”

“…No PTSD-associated differences in hippocampal shape were detected with vertex-based morphometry. Compared to previously published reports of hippocampal subfield volume in PTSD [7], our study used a sample size that was over 2.5 times larger and employed more advanced methods for segmentation of 12 hippocampal subfields based on an atlas constructed from ultra-high resolution MRI scans of postmortem brains.…”

“…Further details of the regression model and regressors are in the Supplement. Results for the CA1, CA3, and DG were not Bonferroni corrected because of prior evidence of volume reduction reported in adults exposed to childhood maltreatment [31] and adult PTSD [6–7]. Regressors in the initial analysis were selected based on established associations with hippocampal volume, but subsequent re-analysis included only regressors with p < 0.15 (see Supplement).…”

The intersection between the oculomotor and hippocampal memory systems: empirical developments and clinical implications

“…Beyond the insights that measures of eye movements can bring to diagnostics, the manner by which visual exploration occurs may provide therapeutic benefits for mental health disorders, such as depression, anxiety, and, in particular, PTSD, for which decreases in hippocampal subfield volume and altered patterns of hippocampal functional connectivity have been observed . Eye movement desensitization and reprocessing (EMDR) is a treatment technique in which emotional or traumatic memories are recalled (such as in the case of PTSD), while lateral saccades are made .…”

Approach‐oriented coping strategy level may be related to volume of the whole hippocampus in the elderly

“…Moreover, previous studies have demonstrated that stress‐related disorders and stress exposure are associated with reductions in the volume of the hippocampus in humans. For instance, cross‐sectional studies have shown that PTSD is related to reductions in hippocampal volume . Additionally, individuals with psychosocial trauma showed reduced hippocampal volume .…”