The Study Of Recognition Of Malingering Memory Impairment In Patietns With Mild Traumatic Brain Injury By FMRI

Background and ObjectiveThe tendency of ma lingering memory impairment is increasing every year inforensic psychiatry practice with the case of memory dama ge in traumatic brain injure(TBI) increases. In recent years, ma ny investigators have paid attention to the study of theneura l passway of feigning memory impairment by a functiona l ma gnetic resona nceima ging (fMRI) test, others also carried out the study of detection of individ ual liar froma group of people, and they obtained ma ny significa nt achievements. However, all thepreceding jobs were carried out in the condition of laboratory, and the memoryimpairment was pretended by health volunteers. Therefore they lack of the identica lextent of mental activities such as tension , anxiety and excitation compared with the realpatients. Moreover, there were less clinica l study about the identity of ma lingeringmemory impairment from the real patients. On account of this question, our prima ryobjective was to investigate whether the patients with TBI feign memory impairment ornot, analyze the difference of their behaviora l data, observe the genera l pattern ofactivated brain regions neura l correla tes and characteristic of neura l circuits and makecomparison with each other.Subjects and MethodA digit forced-choice pattern was adopted in this study, combined with fMRI test. Atotal of 6 (3 men, 3 women) inpatients with acute mTBI involving in economiccompensation took part in this study, and two matched healthy control groups: one groupmade truth response (truth group for short,7 cases), and the other made lie response (liegroup for short,8 cases). The subjects of these three groups were all right-ha nded,andthere were no difference in their ages and educationa l backgrounds. All the subjects wereasked to take digit span test in right order and SCL-90 before scanning, complete theirmemory tasks during scanning. The behavioural data (ie.reaction time) and ima ging datawere recorded while scanning, besides the strategies used for the subjects recorded after scanning.Results1. Neuropsychological test data: Compared with the two healthy control groups,there was no difference about their digit span test in right oder and the factor scores ofSCL-90 such as depression , anxiety and psychotic symptoms between them(P＞0.05).None of them feigned memory impairment in the group of mTBI according to thejudgement of feiging memory impairment in BFDMT: the simple item≤11, the difficultitem≤7, and total≤18.2. Beha vioural data: The reaction time (RT) of the group of mTBI was longer tha ntruth group and shorter tha n lie group, but there was no significa nt difference between thegroup of mTBI and the two healthy control groups(P＞0.05), while the differencebetween lie group and truth group was significa nt(P＜0.01). The accuracy of the groupof mTBI was almost identical with the truth group, and no difference was found betweenthem(P＞0.05), while the accuracy of the group of mTBI and truth group was signific anthigher tha n the lie group(P＜0.01).3. Ima ging data: Compared to the truth group , activations of the bilateral occipitalcuneus and cerebellum were observed in the group of mTBI, and activations of themidd le frontal gyrus(bilatera l), occipital cuneus (bilatera l), cerebellum(bilatera l), leftmed ial occipitotemporal gyrus and left precuneus were observed in the lie group. Whencompared with lie group, the brain regions of posterior cingutate (bilatera l), cerebellum(bilatera l), right midd le temporal gyrus, right lingua l gyrus, right midd le occipital gyrusand right parahippocampal gyrus were activated in the group of mTBI. Compared to thegroup of mTBI, superior temporal gyrus (bila teral), right cingula te gyrus, left midd letemporal gyrus, left superior parietal lobule and left insular lobe were significa nt activatedin the truth group, while significa nt activations were found in the frontal lobe (bilatera l)and left superior parietal gyrus for the lie group.Conclusion1. Inpatients with acute mTBI involving in economic compensation ma y not feignmemory impairment. 2. The brain regions activated in the group of mTBI were common areas involvinga nworking memory process,such as cingula te gyrus, temporal lobe and parietal lobe, andnone of them was the specia l region.3. Bilatera l cerebellum in the group of mTBI were significa nt activated whencompared to the two healthy control groups. Our results suggest that the cerebellum ma ypla y an important part in regulating the cognition process of patients whith mTBI.4. Feigning working memory impairment certainty possess a fronto-parieta lsubcorticalcircuit.