| BackgroundThe pathogenesis of the PTSD is unclear, which may be associated with the structural and functional abnormality in the brain, particularly the hippocampus and amygdala.A neurocircuitry model of PTSD implicates the amygdala, medial prefrontal cortex (mPFC) and hippocampus as dysfunctional in PTSD. However, this neurocircuitry model was based on the MRI studies of the PTSD which was followed by the traumas, such as war, traffic accident and nature disasters, but not by the death of the only child. Whether this neurocircuitry model could apply to the PTSD followed by the death of the only child was unknown. Additionally, there is no literature concerning the structural and functional changes of the brain in such parents with PTSD. Moreover, it was reported that the PTSD patients with different types of trauma may have different cerebral deficits, and some other studies suggested that there may be special inhibition/pathogenesis of the parents with PTSD who had lost their only child and could no longer conceive.The researches on the neurocircuitry could supply theoretical support for the inhibition/pathogenesis and the treatment targets of the diseases. Additionally, MRI could sensitively reflect the disease’s changes in the brain. Therefore, in this study, combining the structural and functional MRI, we aimed to explore the changes in the neurocircuitry of the parents with PTSD who had lost their only child and could no longer conceive.There are three parts in our study:Part One:The hippocampal and amygdala volumes in parents with or without PTSD who had lost their only child and could no longer conceive in China.Objective:To explore the hippocampal and amygdala volume changes in parents with or without PTSD who had lost their only child and could no longer conceive in China.Methods:Hippocampal and amygdala volumes of 57 parents with PTSD (PTSD+),11 trauma-exposed parents without PTSD (PTSD-) and 39 non-traumatized controls were examined using magnetic resonance imaging. Correlations of the volumes with the time since trauma, Clinician-Administered PTSD Scale (CAPS) scores, age, gender and intracranial volume (ICV) were investigated in the PTSD+ group.Result:left hippocampal volumes were significantly smaller in the PTSD+ and PTSD-groups than in the controls, but there were no significant differences between the PTSD+ and PTSD-groups. Furthermore, there was no significant difference in the right hippocampus or bilateral amygdala volumes. Additionally, the hippocampal and amygdala volumes showed no correlation with the time since trauma, CAPS score and gender, whereas the ICV was positively correlated with the left hippocampal volume (b=0.349, P=0.036) and the left and right amygdala volumes (b=0.425, P=0.006 and b=0.412,P=0.005, respectively) in the PTSD+ group. Meaningfully, age was negatively correlated with the left and right amygdala volumes (b=-0.355, P=0.008 and b=-0.300, P=0.018, respectively) but not with the hippocampal volumes in the PTSD+ group.Conclusion:left hippocampal volumes decreased in parents who lost their only child, with or without PTSD. Our results suggest a potentially unique role of the trauma of losing an only child, which is extremely painful and may induce a decrease in the left hippocampal volume independent of PTSD effects.Part Two:The atrophy and laterality of the hippocampal subfields in parents with posttraumatic stress disorder who lost their only child in ChinaObjective:To explore whether the hippocampal subfields were differentially affected in parents in China with PTSD who lost their only child and could no longer conceiveMethods:the whole and subfield hippocampal volumes of 57 parents with PTSD and 39 controls were examined using magnetic resonance imaging. The hippocampal subfields was included the CA1, CA2-3, CA4-DG, subiculum, presubiculum, and fimbria. The relationships of the volumes with the time since trauma and the Clinician-Administered PTSD Scale (CAPS) scores were investigated in the PTSD group.Result:The left whole hippocampal volume, but not the right, was significantly smaller in the PTSD group compared with the controls. The volumes of the bilateral cornu ammonis (CA) 2-3, CA4-dentate gyrus (DG), and left subiculum in the PTSD group were markedly atrophied. Additionally, in the PTSD group, the left whole hippocampus, CA2-3, and CA4-DG volumes were reduced more than those on the right side. The bilateral whole hippocampal volumes, as well as all subfields, were not correlated with the time since the trauma, CAPS score, and gender (P>0.05).In contrast, the ICV was positively correlated with the left hippocampal volume (β= 0.349, P=0.036) and most of the hippocampal subfields (P<0.05). Meanwhile, the age was negatively correlated with the bilateral presubiculum volumes (P=-0.399, P=0.004; β=-0.302, P=0.036, respectively).Conclusion:the parents in China with PTSD who lost their only child showed volumetric reductions of the left whole hippocampus and some subfields with an asymmetry that the left side was affected more than the right. Furthermore, the hippocampal subfields showed differential vulnerabilities to the trauma/PTSD, with CA2-3 and CA4-DG more sensitive than other subfields.Part Three:Amplitude of low-frequency fluctuation in parents with or without PTSD who had lost their only child and could no longer conceive in China:a resting state fMRI studyObjective:To study the changes of amplitude of low-frequency fluctuation (ALFF) of the resting-state functional magnetic resonance imaging (rs-fMRI) in parents with or without PTSD who had lost their only child and could no longer conceive in China.Methods:ALFF in rs-fMRI of 57 parents with PTSD (PTSD+),11 trauma-exposed parents without PTSD (PTSD-) and 39 non-traumatized controls were examined using 3.0T magnetic resonance imaging. The REST and DPARSF were used to preprocess the fMRI data, accounting for ICV, age, and gender.Results:Between the three groups, the analysis of covariance revealed the ALFF values in the right insula, opercularis inferior frontal gyrus, superior temporal gyrus, middle temporal gyrus, and bilateral hippocampus were significantly abnormal. As compared with the control group, the ALFF values in the bilateral hippocampus were significantly decreased in the PTSD+ group, and the ALFF values in the right insula, opercularis inferior frontal gyrus, superior temporal gyrus, and middle temporal gyrus were significantly increased in the PTSD-group. As compared with the PTSD+group, the ALFF values in the right insula, opercularis inferior frontal gyrus, superior temporal gyrus, middle temporal gyrus, and right hippocampus were significantly increased.Conclusion:The pathogenesis of the PTSD disease may be associated with the right insula, opercularis inferior frontal gyrus, superior temporal gyrus, middle temporal gyrus, and bilateral hippocampus in parents who had lost their only child and could no longer conceive in China. The decreased activation in the bilateral hippocampus may lead to the development of the PTSD disease, and the increased activation in the right insula, superior temporal gyrus and middle temporal gyrus may be associated with the inhibition of the PTSD disease in parents who had lost their only child and could no longer conceive.
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