Application Of Premorbid IQ Evaluation In Forensic Psychiatric Appraisal For Patients With Traumatic Brain Injury

ObjectiveThe intellectual impairment of patients with traumatic brain injury(TBI) caused by traffic accidents, etc. is very common. Parties with TBI caused by traffic accidents, etc. often ask the opposing party for compensation on the ground of intellectual impairment in forensic psychiatry. The degree of intellectual impairment can be got by comparing the current IQ and the premorbid IQ. There are many intuitive and standard measurement methods to get the current IQ, but it's hard to get the intelligence data before injury. I's hard to assess the intellectual impairment degree because we're lack of objective indicators of the premorbid IQ, so we usually convert methods of estimating the intelligence impairment to the classification of dysnusia, but the dysnusia and the intellectual impairment are two different concepts, so the forensic examination conclusions will be unreasonable. The premorbid IQ estimation is of great significance in forensic psychiatry in estimating the degree of intelligence decline of patients with TBI. This subject is to study the application of premobid IQ estimation with the multiple regression formula of WAIS-RC in clinical and forensic psychiatry of patients with TBI and the related factors through the neuropsychological tests and assessment of the litigation group,the non-litigation group and the healthy group, in order to provide some information to improve the accuracy of estimating premorbid IQ. At the same time, we compared the application of the short forms of WAIS-RC and the full scale in patients with TBI to study the application value of the short forms in clinical and forensic psychiatry.Subjects and MethodThe litigation group patients came from Chaonan-Minsheng hospital of Shantou and forensic appraisement center of Shantou University Medical College (54 cases). The non-litigation group patients came from Chaonan-Minsheng hospital of Shantou(52 cases). The healthy group was composed of healthy volunteers who came from the city of Shantou, Shantou University Medical College, Mental health center of Shantou University and Chaonan area(28 cases).Three groups were given the GCS assessment, an intelligence test(WAIS-RC), the premobid IQ estimation(the multiple regression formula of WAIS-RC in estimating premorbid IQ) and short forms assessment of WAIS-RC, and the data were statistically analyzed.Results(1) There was no statistically significant difference between litigation group and non-litigation group in gender, age and years of education(P>0.05). there was no statistically significant difference between litigation group, non-litigation group and the normal group in gender and age(P>0.05), but the years of education of TBI goup are lower than the normal group.(2) The differences between litigation group and non-litigation group in FIQ, VIQ and PIQ were highly statistically significant (P<0.01).(3) The scale score differences between litigation group and non-litigation group were highly statistically significant in Information, Arithmetic, Similarities, Vocabulary, Picture Completion and Picture Arrangement (P<0.01). The scale score differences between the two groups were statistical significance in Digit Span and Block Design(P<0.05). There was no statistically significant scale score difference between the two groups in Comprehension, Digit Symbol-Coding and Object Assembly.(4) There were no statistically significant difference between litigation group and non-litigation group in Pre-FIQ ,Pre-VIQ and Pre-PIQ.(5) Differences between Pre-FIQ and FIQ, Pre-VIQ and VIQ and Pre-PIQ and PIQ in all patients with TBI and the litigation group were highly statistically significant (P<0.01). Differences between Pre-FIQ and FIQ and Pre-VIQ and VIQ in non-litigation group were highly statistically significant (P<0.01), and differences between Pre-PIQ and PIQ in non-litigation group were statistically significant(P<0.05).(6) There were highly statistically significant difference between Pre-FIQ and FIQ in patients with mild, moderate and severe TBI (P<0.01). The average of premorbid IQs is higher than the average of the current IQs in all patients with TBI.(7) Patients of all patients with TBI and the litigation group with more severe head injuries demonstrated a larger discrepancy between the estimate of premorbid IQ and current obtained IQ . Patients of the non-litigation group with mild injury demonstrated a smaller discrepancy between the estimate of premorbid IQ and current obtained IQ, and with moderate injury ,a larger discrepancy.(8) There were highly statistically significant difference between Pre-FIQ and FIQ in normal group(P<0.01). The average of the estimate of premorbid IQs was lower than the average of the current obtained IQs in normal group.(9) The correlations between full scale IQs and the two-subtest short form IQ estimates were 0.564~0.868 in all subjects(of which the six-subtest short form IQs were the most relevent). Differences between the means of the short form IQs and the full scale IQs were all significant in the four-subtest short form (I,S,PC,BD)IQs,but were not significant in other short forms IQs. the level of agreement of the six-subtest short form on the full scale IQs is higher than that of other short forms on the full scale IQs.Conclusions(1) The multiple regression formula of WAIS-RC in estimating premorbid IQ is accurate for patients with TBI, but is easy to underestimate the premorbid IQ of the high intelligence.(2) There're intellectual impairments in both litigation group and non-litigation group. The current obtained IQs of litigation group are lower than those of non-litigation group, and we considered that patients with TBI may have consciously exaggerated the degree of the intelligence impairment because of litigation.(3) Performances of the sub-tests of the intelligence test were different between litigation group and non-litigation group. We considered that performances of litigation group in Information and Arithmetic sub-tests were lower than the actual scores, but performances of patients with TBI were the same in the Comprehension, Digit Symbol-Coding and Object Assembly sub-tests whether or not there's litigation factor. Because most of the subjects were mild or moderate TBIs, we cann't entirely sure about the obove conclusions.(4) All the patients with mild to severe TBI had intelligence imparment in varying degrees. This mothod of estimation of premorbid IQ is sensitive to the severity of TBI. The litigation factor had a certain influence on estimating premorbid IQ.(5) )There's no reduction in the reliability of the short forms of WAIS-RC whether or not by litigation factors. The short forms of WAIS-RC is more accuracy to patients with TBI whose IQ are more than 90.(6) The application of the six-subtest short form is more consistent with the full scale of WAIS-RC in clinical and forensic psychiatry when we cann't use the full scale of WAIS-RC in objective or subjective reasons.