Abstract
It has been found that Duchenne muscular dystrophied children often obtain the performance IQ scores that are higher than their verbal IQ scores on the WISC. The present study was undertaken to investigate the effect of language development on this discrepancy between verbal and performance IQs. The WISC and the ITPA were administered to 24 boys with Duchenne muscular dystrophy. As a result of the WISC, the mean full IQ 74.3, verbal IQ 70.8 and performance IQ 83.3 were obtained. This mean verbal IQ was significantly lower than the performance. And 15 in the 24 boys studied had the discrepancy that performance IQ scores were higher of more than 6 IQ points over verbal IQ scores. Based on the discrepancy, we subdivided our cases into discrepancy group (D group, n =15) and non-discrepancy group (ND group, n=9). The results of the WISC and the ITPA of D group were compaired with those of ND group. Neither the WISC full IQ nor the ITPA global score differed significantly. In analysing the WISC and the ITPA subtest scores, D group showed the lower mean scores than ND group on all the subtests which asked to response by verbal expression and showed the higher mean scores than ND group on all the subtests which asked to response by non-verbal expression. From these findings, we hypothesized that the discrepancy resulted from verbal expression. And further we carried out the following test to verify our hypothesis. We changed the procedure of "Information" of the WISC subtest, and this subtest was administered to each 5 subjects among D and ND group. Namingly the procedure of this subtest were substituted pointing for verbal responce. As a result, while there were an increase of the mean 2.2 scores in ND group, there were an increase of the mean 4.2 scores in D group. An increase differed significantly between two groups.
