| Introduction and ObjectiveThe reliable evaluation of mental injury caused by PTSD has been a difficult issue in forensic psychiatry,because of subjective,unstable and equivocal results.Animal studys indicated that stress could damage the neuron of hippocampus.Hippocampal atrophy and metabolites level decrease have been found in and ex vivo studies of animal after chronic stress, which is positive correlate with the stress intensity.Researches on PTSD of human being also found whose hippocampal volune and metabolites levele changed.This study applying magnetic resonance imaging(MRI) and magnetic resonance spectroscopy(MRS) to determin hippocapal volume and metabolites level(NAA/Cr) in vivo,combining with the scores on CAPS and ISE-R and the serum level of cortisol and FT3 to explore the neurochemistry mechanism of hippocampal damage induced by PTSD,and analyze the relationship amone hippocampal volume,NAA level,severity of symptom(the scores on CAPS and ISE-R) and neuroendocrine. In order to establish the evaluation multiple factor model of PTSD and provide experimental basis for the evaluation of mental injury caused by PTSD.Materials and MethodsThe subjects were recruited through advertising and contacts with inpatient and outpatient from April 2006 to July 2007 in mental health center of peoples hospital of Wuhan university in hubei province.Among the patients with a possible diagnosis of PTDS that were evaluated by two associate chief psychiatrists.At last,14 aged from 18 to 55 meeting the diagnostic criteria of the disease according to the Diagnostic and Statistical Manual of Mental Disorders-Ⅳ(DSM-Ⅳ) were included.The exclusion criteria were alcohol or substance abuse during the last six months, endocrine diseaed and nervous syetem disease,depression and other psychiatry disease,and known contraindications to MR imaging such as pregnancy and the presence of metal prostheses, implants,etc.Symptomatology and symptom severity were assessed with the Clinician Administered PTSD scale and the impact of event scale-revised.14 age,gender and educated time matched normal healthy groups(control groups) were included too.After a complete description of the study to the subjects,written informed consent was obtained.All subjects were examined on a GE 1.5T MRI/MRS system.Magnetic resonance spectrum imagings were obtained from two sides of the hippocampus region.The metabolites included N-acetylaspartate(NAA),creatine and phosphocreatine(Cr),and choline-containingcompounds (Cho).The values of NAA,Cr and Cho were calculated by integration of their peaks.The volume of the hippocampus of the two sides and the brain volume were measured with volume analysis software,and the resulting data were normalized according to the individual brain volume.The data were analyzed by t test,Pearson relation analysis and stepwise multiple regression of variance with SPSS 13.0 for Windows.Results(1) The age and educated time are no sifnificant difference between PTSD and control group;the total and negative scores on LES of PTSD(58.434±37.53,25.07±23.53) are higher than control group(46.71±31.05,13.29±11.90),P＜0.05.(2) Compared with control group,the PTSD group has higher serum corticosterone and FT3 concentration,the difference has statistical significance,P＜0.05.(3) The volume of left hippocampus of PTSD(3378±253.1) was smaller than that of the control subjects(3671±324.8),P＜0.05,but there was no significant difference between PTSD (3332±185.1) and control subjects(3529±338.7) in the right hippocampus,P＞0.05.(4) NAA/Cr significantly reduced in PTSD(Left:1.153±0.092;Right:1.271±0.077) bilaterally when compared with those of control subjects(Left:1.3634±0.094;Right:1.351±0.101) (P＜0.05).Cho/Cr had significant difference in the right side hippocampus between PTSD (1.094±0.087) and control subjects(1.011±0.069),P＜0.05.(5) The NAA/Cr(1.104±0.094) in PTSD patients whose age no less than 40 was significant lower than the others(1.218±0.032),P＜0.05;but the volume of bilateral hippocampus didn't find diffference between two groups.There were no significant difference between bilateral hippocampal metabolin level and volume in gender,personality,educated time,occupation and the disease course of patients.(6) Serum corticosterone and FT3 concentration of PTSD patients are negative relate to left and fight hippocampal NAA/Cr,coefficient is -0.229,-0.448,-0.331 and -0.250, P＞0.05.The total score on ISE-R and CAPS are significant correlate to left hippocampal metabolites level NAA/Cr and volume,(r=-0.823,-0.921,-0.912 and -0.939),P＜0.01;The total score on ISE-R and CAPS are correlate to right hippocampal metabolites level NAA/Cr and volume,P＞0.05.There are significant clrrelation between volume and metabolites in left and right hippocampus of PTSD patients,r=0.883 and 0.553,P＜0.05.(7) Multiple regression analysis:the total score on CAPS and ISE-R are dependent variable (Y1) and(Y2) respectively,NAA/Cr of left hippocampal(X1) and left hippocampal volume(X2) are inlet into equation as independent variables(significance level for selecting variables: P=0.05),stepwise multiple regression equation is:Y1= 250.1-0.002X1-76.47X2; Y2128.9-39.47X1-0.092X2.Conclusions(1) The serum level of cortisol and FT3 is elevated in PTSD patients.(2) The left hippocampal volume is reduce significant and significant negative relate to the severity of PTSD.(3) The bilateral hippocampal metabolites level NAA/Cr of PTSD is significant lower than control group,NAA/Cr in the left hippocampus is negative relate to the severity of PTSD.(4) Compared with right hippocampus,the left hippocampus is more sensitive to traumatic event and its neuron easier to injury.(5) The metabolites level and volume of hippocampal could reflect the degree of patients' mental injury saitivity and the former is more sensitive than the latter.(6) The severity of mental injury caused by PTSD may calculated from following multiple regression:Y1=250.1 - 76.47X1 - 0.002X2 and Y2 = 128.9- 39.47X1 - 0.092 X2.
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