| ObjectionExperiment 1:To analysis reliability, validity and the correlative factors of the Chinese Paced Auditory Serial Addition Test (PASAT).Experiment 2:To explore whether the decline of information processing speed or accuracy is the main defect in multiple sclerosis with working memory disorder, based on the working memory conception of Baddeley, and the relation of working memory dysfunction and other cognitive impairment in multiple sclerosisMethodExperiment 1:All the healthy subjects were assessed with PASAT, the Mini-mental State Examination (MMSE), the Hamilton Depression Rating Scale, the Fatigue Severity Scale and the Pittsburgh Sleep Quality Index. After 7±2 days of the initial assessment,20 of the subjects were enrolled in the test-retest reliability and scorer reliability test, and 41 were taken into the construct validity test which included other 10 neuropsychological tests such as the Prospective Memory Test, the Chinese Rey Auditory Verbal Learning Test, the Symbol Digit Modalities Test, the Trail Making Test and so on.Experiment 2:From the settings of the Nan Fang Hospital and the Guangdong Province Traditional Chinese Medicine Hospital, twenty adults with clinically definite multiple sclerosis (MS), as diagnosed by board-certified neurologists with a specialization in MS (McDonal et al.,2004), were enrolled in this study, from May 2010 to February 2010. There were 3 patients (female,62 year-old,53 year-old,37 year-old) failing to complete the whole study. Therefore,17 MS participants participated in this study. The control sample consisted of 17 healthy individuals whom were selected according to the ration of 1:1 matched in gender, age (a difference of less than 3 years old), and education years (a difference of less than 5 years). In a independent and quiet room, all the subjects were evaluated by a specialist doctors and administered assessments in the following order:(1) general information survey (including name, gender, age, education years, past history, family history, drug use, smoking, and alcohol consumption); (2) MS disease survey (which was just for MS subjects, including MS type, EDSS score, onset time, relapse frequency, the main symptoms, and imaging findings); (3) neuropsychological tests (including the Chinese Paced Auditory Serial Addition Test, the 2-Back Task, the Chinese Rey Auditory Verbal Learning Test Nl-7, MMSE, the Verbal Fluency Test, the Symbol Digit Modalities Test, the Chinese Trail Making Test, the Digit Span Test, the Chinese version of the Stroop Colour-Word Test, the Similarity Test, the Chinese Rey Auditory Verbal Learning Test N8-9, the Clock Drawing Test, and the Rey Complex Figure Test-learning);(4) other neuropsychological assessments (including Hamilton Depression Rating Scale, Fatigue Severity Scale, and Pittsburgh sleep quality index); (5) the Rey Complex Figure Test-recalling. This study used statistical software SPSS 13.0 for statistical analysis. After testing the normality and the homogeneity, the data were calculated with the use of the rank test to compare groups differences in mean rank or, if permitted, by a t-test to compare groups differences in means. Reference to the method used in previous MS studies (DeLuca et al.2004), the 5% of the healthy matched group's scores on the Symbol Digit Modalities Test (SDMT) used as the cut-off or determining dysfunction in working memory. The participators with MS who performed below the 5% were considered as "SDMT-impairment", on the other side, they were seen as "SDMT-retainer". Besides, the thought of the Mean Standardized Method was used to compare the results of working memory tests in SDMT-impairment. Details of the formula see the text. Test levelα=0.05, with P <0.05 as significant difference, choose two-sided test.ResultExperiment 1:The internal consistency reliability (cronbach'sα=0.900), test-retest reliability (ICC=0.837, P=0.000), score reliability (ICC=0.999, P=0.000) of the Chinese PASAT were generally high. Practice effect were observed in short term (Z=-3.304, P=0.001). Executive function, working memory, verbal memory, time based prospective memory and the ability of logic reasoning were involved to complete the task of PAS AT. There was a significant positive correlation of the PASAT results and the education years(r=0.582, P=0.000).Experiment 2:(P=)(1) There was no significant difference between the MS group and the healthy group on the accuracy of simple working memory tests such as the Digit Span Test (DS, P=0.169), the Stroop-Word Correct (Stroop-wc, P=0.482), Stroop-Color Correct (Stroop-cc, P=0.623), Stroop-Interference Correct (Stroop-ic, P=0.456); On the other hand, MS group show significant impairment on the working memory tests with higher time requirement, such as PASAT-3'(P=0.007). PASAT-2'(P=0.014),SDMT (P=0.007),the 2-Back task (2-Back, P=0.011), and the time-consuming of the simple working memory tests like Stroop-Color time (P=0.044) and Stroop-Interference Correct(P=0.025).(2) As to the results of other neuropsychological tests, except the the Rey Complex Figure Test (RCFT), the Trail Making Test (TMT)-B Errors, and the Verbal Fluency Test (VF), other results present statistically significant difference between two groups (P<0.05). The average ranks of MS are lower than the healthy group on the tests with positive score rule which are MMSE (P=0.010), the Clock Drawing test (P=0.007), total score of the Chinese Rey Auditory Verbal Learning Test (CRAVLT, P =0.001), and the Similarity test (SMI, P=0.004), and the mean ranks of MS group are higher than the healthy group on the tests with negative score rule like TMT-A Time (P=0.000), TMT-B Time (P=0.000), and TMT-A Errors (P=0.004).(3) In terms of working memory, one of the MS subgroups, SDMT-retainer have lower mean ranks on PASAT/SDMT/DS, while higher mean ranks on the Stroop test/2-Back compared with healthy group, but no significant difference were observed (P>0.05). SDMT-impairment also find the same on DS (P>0.05). There are large difference between the SDMT-impairment and healthy group on the positive score tests like PASAT/SDMT and the negative score tests like 2-Back, which achieve statistical significance. The SDMT-impairment spend more time than healthy group on the Stroop test (P<0.05), while the accuracy of the Stroop test show no difference (P>0.05).(4) It is obviously that both the subgroups performed worsen on the verbal learning test of CRAVLT-total score and TMT respectively (P<0.05), when compared with controls. Besides, SDMT-impairment also obtained poorer results on MMSE/ CDT/SIMI/VF (P<0.05) than healthy group. In contrast, the opposite situation that both subgroups achieve the same level of the control in RCFT (P>0.05) is observed.(5) After standardization of the working memory tests scores, the standardize mean value of SDMT is the lowest in SDMT-impairment (0.468), followed by PASAT-3'(0.622)/Stroop-wt (0.624)/PASAT-2'(0.656)/Stroop-ct (0.677)/Stroop-it (0.728). The standardize mean values of DS (0.821) and 2-Back (0.809) are closer to 1, which means that the level of damage on these tests relatively less than previous ones. The evidences from RCFT-learning and RCFT-recall that both values are more than 1 (1.119 and 1.099) suggest the SDMT-impairment with visuospatial ability retaining.ConclusionExperiment 1:The Chinese PASAT has good reliability and validity for Chinese young and middle-aged people. Years of education and the Chinese PASAT were significantly related. On the other hand, the relationship of the Chinese PASAT and other factors, such as age and gender, should be further explored in futureExperiment 2:This study suggests several possibilities as follow:(1) At the tests with lower requirement for central executive function like DS and the Stroop test, MS subjects spend more processing time but the accuracy of information processing is not affected. On the other hand, at the tests with higher central executive load like PASAT/2-Back, MS subjects preformed poor on both processing speed and accuracy which suggest the a possibility that they would sacrifice the accuracy of central executive function to make up a greater gap in the information processing speed. (2) New semantic information learning and processing disorders may be the most vulnerable aspects involved in MS with cognitive impairment for both the subgroups with MS showed impairments in CRAVLT. However, the MS groups did not show any obvious defects on the spatial structure test, RCFT. It is possible that, for the visual spatial information executing, individual with MS still retain its feeling encoding rather than its semantic encoding. Therefore, the new spatial information learning and processing relatively retain in adults with MS. After all, the study is also limited by the small sample size. It is necessary to expand the sample size and further improve the experimental design in future. |
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