Research reportSmaller volume of anterior cingulate cortex in abuse-related posttraumatic stress disorder
Introduction
Posttraumatic stress disorder (PTSD) is a highly prevalent disorder affecting 8% of the population by some estimates (Kessler et al., 1995). Understanding the neurobiology of PTSD is important for the development of new treatments for this disorder. The medial prefrontal cortex, a brain area which makes up a part of the frontal lobe, plays an important role in the negative feedback regulation of hypothalamic–pituitary–adrenal (HPA) activity during physiologic and behavioral stress. In recent animal studies, repeated restraint stress or corticosterone injections induced apical dendritic reorganization by reducing total branch number of pyramidal neurons in the anterior cingulate cortex (ACC) (Radley et al., 2005, Cerqueira et al., 2005a, Cerqueira et al., 2005b). Furthermore, neuroimaging studies demonstrated functional and morphologic abnormalities in ACC of the patients with PTSD. Brain functional studies using positron emission tomography (PET) or functional magnetic resonance imaging (fMRI) showed decreased function in ACC (Bremner et al., 2004, Bremner et al., 1999, Yang et al., 2004, Lanius et al., 2003, Shin et al., 2001), and morphometric MRI studies demonstrated smaller volume of the ACC (Rauch et al., 2003, Yamasue et al., 2003) in comparison to non-PTSD subjects. However, volumetric studies of ACC in PTSD using MRI have had conflicting findings; one study using the conventional manual tracing method found significant volume reduction in pregenual ACC but not in dorsal ACC (Brodmann's area [BA] 24) (Rauch et al., 2003), and the other using voxel-based analysis found a gray-matter volume reduction in dorsal ACC (Yamasue et al., 2003). Additionally, there was no difference in ACC volume between acute PTSD and healthy subjects but was found shape differences in a recent study (Corbo et al., 2005). However, no studies have examined the effects of early childhood abuse and PTSD on ACC volume. The purpose of the current study was to clarify the structural changes of ACC in subjects with abuse-related PTSD.
Section snippets
Method
Magnetic resonance imaging was used to measure ACC volume in 8 subjects with abuse-related PTSD (7 women and 1 man, mean = 43 years, S.D. = 7) and 13 control subjects without current or past history of PTSD or other psychiatry disorder (12 women and 1 man, mean = 37, S.D. = 8). The 8 subjects with PTSD met DSM-IV criteria for current PTSD, according to the Clinician Administered PTSD Scale (CAPS; mean score = 70, S.D. = 37). All of the subjects were recruited in New Heaven, Connecticut, USA. Psychiatric
Results
As shown in Fig. 2, the absolute volumes of “Whole ACC” volume in patients with PTSD were: Right: 1112.2 ± 183.8; Left: 1116.4 ± 196.5, and in non-PTSD controls: Right: 1376.3 ± 295.4; Left: 1334.6 ± 302.5 (mm3; AVE ± S.D.). The volumes of “Partial ACC” volume in patients with PTSD were: Right: 780.6 ± 150.4; Left: 802.7 ± 226.0, and in non-PTSD controls: Right: 822.1 ± 170.6; Left: 764.8 ± 119.6 (mm3; AVE ± S.D.). According to these results, “Whole ACC” volume on the right side in PTSD patients was significantly
Discussion
In the present study, right dorsal ACC volume in PTSD, including both BA 24 and 32, was significantly smaller than in non-PTSD. This area corresponds to the region of decreased function reported for ACC in functional imaging studies (Bremner et al., 2004, Yang et al., 2004, Lanius et al., 2003, Shin et al., 2001). In addition, there was no significant difference in partial ACC volume, including only BA 24 in PTSD in comparison to the non-PTSD controls. This result mostly agrees to a previous
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