Studies in nonhuman primates suggest that high levels of cortisol associated with stress have neurotoxic effects on the hippocampus, a brain structure involved in memory. The authors previously showed that patients with combat-related posttraumatic stress disorder (PTSD) had deficits in short-term memory. The purpose of this study was to compare the hippocampal volume of patients with PTSD to that of subjects without psychiatric disorder.
Magnetic resonance imaging was used to measure the volume of the hippocampus in 26 Vietnam combat veterans with PTSD and 22 comparison subjects selected to be similar to the patients in age, sex, race, years of education, socioeconomic status, body size, and years of alcohol abuse.
The PTSD patients had a statistically significant 8% smaller right hippocampal volume relative to that of the comparison subjects, but there was no difference in the volume of other brain regions (caudate and temporal lobe). Deficits in short-term verbal memory as measured with the Wechsler Memory Scale were associated with smaller right hippocampal volume in the PTSD patients only.
These findings are consistent with a smaller right hippocampal volume in PTSD that is associated with functional deficits in verbal memory.
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"During the past decade, growing interest has been paid to the neurobiological basis of posttraumatic stress disorder (PTSD), typically indicating structural brain modifications of several grey matter formations following trauma exposure, though these results are still subject to debate. The most noticeable morphological alterations in PTSD in magnetic resonance imaging (MRI) studies were found in limbic structures, with consistent observations of hippocampal atrophy (Bremner et al., 1995, 2003; Stein et al., 1997; Gurvits et al., 1996; Lindauer et al., 2005; Kasai et al., 2008; Pavić et al., 2007; Shin et al., 2004; Pavlisa et al., 2006). 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). "
"Over the past 20 years, a large literature of neuroimaging studies investigating the structural brain changes associated with PTSD has emerged. While important initial investigations revealed PTSDrelated volumetric reductions in hippocampus (Bremner et al., 1995; Gurvits et al., 1996; Stein et al., 1997), subsequent studies have described gray matter volume (GMV) reductions extending throughout limbic and paralimbic structures, as well as prefrontal cortical regions (Aupperle et al., 2013; Chen et al., 2006; Geuze et al., 2008; Keding and Herringa, 2015; Kuhn and Gallinat, 2013; Nardo et al., 2010; Rauch et al., 2003; Yamasue et al., 2003). To date, an inverse relationship between limbic/paralimbic GMV and PTSD severity, as well as the severity of the individual symptom clusters of re-experiencing, avoidance/numbing, and hyperarousal, has predominated (Araki et al., 2005; Kroes et al., 2011; Lindauer et al., 2004; Shucard et al., 2012; Thomaes et al., 2010; Villarreal et al., 2002; Yamasue et al., 2003); yet, other reports of positive associations between PTSD and early life trauma severity, and hippocampal/amygdala volume have also been reported (Baldacara et al., 2014; Weber et al., 2013). "
[Show abstract][Hide abstract] ABSTRACT: Despite the anatomical overlap between the brain's fear/threat and olfactory systems, a very limited number of investigations have considered the role of odors and the central olfactory system in the pathophysiology of PTSD. The goal of the present study was to assess structural differences in primary and secondary olfactory cortex between combat veterans with and without PTSD (CV + PTSD, CV-PTSD, respectively). An additional goal was to determine the relationship between gray matter volume (GMV) in olfactory cortex and the distressing properties of burning-related odors. A region of interest voxel-based morphometric (VBM) approach was used to measure GMV in olfactory cortex in a well-characterized group of CV + PTSD (n = 20) and CV-PTSD (n = 25). Prior to the MRI exam, combat-related (i.e., burning rubber) and control odors were systematically sampled and rated according to their potential for eliciting PTSD symptoms. Results showed that CV + PTSD exhibited significantly reduced GMV in anterior piriform (primary olfactory) and orbitofrontal (secondary olfactory) cortices compared to CV-PTSD (both p < .01). For the entire group, GMV in bilateral anterior piriform cortex was inversely related to burning rubber odor-elicited memories of trauma (p < .05). GMV in orbitofrontal cortex was inversely related to both clinical and laboratory measures of PTSD symptoms (all p < .05). In addition to replicating an established inverse relationship between GMV in anxiety-associated brain structures and PTSD symptomatology, the present study extends those findings by being the first report of volumetric decreases in olfactory cortex that are inversely related to odor-elicited PTSD symptoms. Potential mechanisms underlying these findings are discussed.
Journal of Psychiatric Research 08/2015; 70. DOI:10.1016/j.jpsychires.2015.08.015 · 3.96 Impact Factor
"cits in their declarative memory, even for events that have nothing to do with the original trauma (Bremner et al., 1995, 1997). These deficits are the result of lasting damage to the hippocampus, due to synaptic loss caused by adrenal steroids; such people are especially prone to further hippocampal damage caused by ongoing high levels of stress (reviewed in Kandel, 1999, and LeDoux, 1996). "