Abstract
Solomon, Greene, Farr, and Kelly in 1986 speculated that large discrepancies between Intelligence and Memory quotients (IQ-MQ) reflecting poorer performance on memory casks may be due to focal brain damage, while smaller differences may result from diffuse damage. The present study investigated this hypothesis in a rehabilitation population with sufferers of unilateral cerebrovascular accidents (CVA) representing focal damage and those with closed-head injury (CHI) representing diffuse damage. The IQ-MQ discrepancy was examined in two samples, one administered the Wechsler Adult Intelligence Scale (WAIS) and the other the WAIS—R. Analysis of covariance indicated that IQ-MQ was significantly different for the two groups administered the WAIS—R but not the WAIS. However, the direction of the difference in discrepancy score was opposite that posited by Solomon, et al., i.e., relatively poorer memory was observed in patients with diffuse damage. Results are discussed in relation to demographic differences between the two kinds of patients and the inability to remove effects of group differences by using analysis of covariance as well as neuropathological factors that confound focal and diffuse injury in subjects showing closed-head injury and cerebrovascular injury. Finally, the effect on IQ-MQ discrepancy scores based on the WAIS—R is discussed in light of previously held “rules of thumb” about clinically significant differences.
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