Size Versus Shape Differences: Contrasting Voxel-Based and Volumetric Analyses of the Anterior Cingulate Cortex in Individuals with Acute Posttraumatic Stress Disorder

Douglas Hospital Research Center, Department of Psychiatry, Montreal, Quebec, Canada.
Biological Psychiatry (Impact Factor: 10.26). 08/2005; 58(2):119-24. DOI: 10.1016/j.biopsych.2005.02.032
Source: PubMed


Two studies found morphological differences in the anterior cingulate cortex (ACC) of individuals with chronic posttraumatic stress disorder (PTSD). We sought to replicate and extend these findings in a sample of individuals with acute PTSD.
The ACCs of individuals with acute PTSD (n = 14) and matched healthy control subjects (n = 14) were compared using voxel-based morphometry (VBM), semi-automated volumetric analyses, and probabilistic maps. Posttraumatic stress disorder diagnosis was ascertained by a psychologist using a structured interview.
Voxel-based morphometry analyses revealed significantly less gray-matter density in the right pregenual ACC and in the left insula of the PTSD group. However, volumetric analyses of the ACC revealed no significant differences between groups. Probabilistic maps of the labels of the pregenual ACC indicated that the difference between groups in gray matter density was due to shape differences.
Although there are no volumetric differences in the ACC of acute PTSD individuals compared with normal control subjects, significant shape differences exist, which might indicate volumetric differences in the surrounding structures.

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    • "Other PTSD-related volumetric reductions were noticed in the amygdala (Pavlisa et al., 2006), anterior cingulate gyrus (Rauch et al., 2003; Woodward et al., 2006a,b), corpus callosum (Villarreal et al., 2004), cerebellum (De Bellis and Kuchibhatla, 2006), and temporal and frontal grey matter (Geuze et al., 2008). Conversely, an important number of studies failed to demonstrate PTSD stateassociated atrophies in the hippocampus (Fennema-Notestine et al., 2002; Golier et al., 2005; Hedges et al., 2007; Neylan et al., 2004; Pederson et al., 2004; Schuff et al., 2001, 2008; Woodward et al., 2006a,b; Gilbertson et al., 2002) as the amygdala (Gurvits et al., 1996; Fennema- Notestine et al., 2002) and the anterior cingulate gyrus (Corbo et al., 2005). These discrepancies in MRI-based PTSD studies may be attributed to various study characteristics, such as sampling (sample size, age, and gender), type of traumatic experiences (e.g. "
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    • "). PTSD related abnormalities however are not only functional. Gray matter volume loss or cortical thinning have also been described and are most commonly found in the hippocampus and the mesial prefrontal cortex, particularly anterior cingulate, but occasionally also in the dorsolateral prefrontal and orbitofrontal and insular cortices (Carbo et al.2005;, Geuze et al. 2008, Woon et al. 2010, Karl et al. 2006, Eckart et al. 2011, Kuehn et al. 2011, Rauch et al. 2003, Yamasue et al. 2003), i.e., in the same regions that are affected by the "
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    ABSTRACT: Posttraumatic stress disorder (PTSD) is characterized by atrophy within the prefrontal-limbic network. Graph analysis was used to investigate to what degree atrophy in PTSD is associated with impaired structural connectivity within prefrontal limbic network (restricted) and how this affects the integration of the prefrontal limbic network with the rest of the brain (whole-brain). 85 male veterans (45 PTSD neg, 40 PTSD pos) underwent volumetric MRI on a 3T MR. Subfield volumes were obtained using a manual labeling scheme and cortical thickness measurements and subcortical volumes from FreeSurfer. Regression analysis was used to identify regions with volume loss. Graph analytical Toolbox (GAT) was used for graph-analysis. PTSD pos had a thinner rostral anterior cingulate and insular cortex but no hippocampal volume loss. PTSD was characterized by decreased nodal degree (orbitofrontal, anterior cingulate) and clustering coefficients (thalamus) but increased nodal betweenness (insula, orbitofrontal) and a reduced small world index in the whole brain analysis and by orbitofrontal and insular nodes with increased nodal degree, clustering coefficient and nodal betweenness in the restricted analysis. PTSD associated atrophy in the prefrontal-limbic network results in an increased structural connectivity within that network that negatively affected its integration with the rest of the brain.
    Psychiatry Research: Neuroimaging 09/2015; 234(2). DOI:10.1016/j.pscychresns.2015.09.006 · 2.42 Impact Factor
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    • "Several other studies have reported similar negative findings [Jorge et al., 2012; Morey et al., 2012; Taber et al., 2015] although two studies using different diffusion metrics suggest white matter involvement in PTSD [Bazarian et al., 2012; Davenport et al., 2015]. Nonetheless, PTSD-related neuropathology appears to be associated primarily with changes in gray matter volume [Bremner et al., 1995; Corbo et al., 2005; Kasai et al., 2008; O'Doherty et al., 2015; Smith, 2005] and functional alterations [Bremner et al., 1999; Daniels et al., 2010; Hayes et al., 2011; Milad et al., 2009; Sadeh et al., 2015; Shin and Liberzon , 2010; Shin et al., 2004; St Jacques et al., 2013; van Wingen et al., 2012]. Further research is needed to determine if PTSD-related neuropathology independently mediates the relationship between PTSD and PCS severity. "
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