Summary

This chapter is the first of two on V-P IQ discrepancies and covers the following topics, all related to the neuropsychological interpretation of these verbal-nonverbal differences: (1) Wechsler-Bellevue, WAIS, WAIS-R, and WAIS-III V-P studies of neurological patients having damage confined to the left or right hemisphere;

(2) WAIS-III studies of neurological patients with diffuse brain damage, focusing on the factor index profile; (3) relationship of the nature of brain damage (type, acuteness versus chronicity) to V-P discrepancy; (4) subtest patterns for pa tients with left or right lesions; (5) the interaction of gender and ethnicity with V-P discrepancies in brain damage; (6) the interaction of age and education with V-P discrepancies in brain damage.

The results of over 50 studies involving the testing of nearly 2,700 patients with unilateral brain damage on the W-B I, WAIS, and WAIS-R give basic support to the long-held contention that left-lesion patients have characteristic P > V profiles, while right-lesion patients show V > P discrepancies. However, the support is far more impressive for patients with right-hemisphere damage. Across all studies, the latter group averaged a 9-point Verbal IQ superiority compared to about a 3^2-point Performance advantage for left-lesion patients. WAIS and WAIS-R studies were generally less impressive regarding the predicted V-P profiles than were the studies conducted with the W-B I. Most notably, left-lesion patients showed an average P > V difference of about 2 points on the WAIS and WAIS-R compared to a 71/2-point discrepancy on the older battery. Because no data were available on the WAIS-III and lateralized lesions, we focused on the information available on diffuse brain injury and the WAIS-III. The most notable finding for recent (since 1988) studies of diffuse brain damage on the WAIS-R and WAIS-III was a V > P pattern. However, three studies of factor indexes on the WAIS-III produced even more provocative findings for patients with diffuse lesions as a result of traumatic brain injury, intact Perceptual Organization coupled with weak Processing Speed.

The degree to which predicted V-P discrepancies accompany left or right lesions depends on the type of lesion. Strokes tend to produce dramatic V-P differences in the predicted direction, especially for males. Patients with tumors in the right hemisphere display V > P profiles, but those with left-hemisphere tumors evidence no V-P difference. Patients with temporal lobe epilepsy show the predicted pattern for patients having lesions in the left as well as right hemisphere, although the mean discrepancies are modest in magnitude. Lateralized frontal lobe lesions, whether caused by missile wounds or tumors, have little impact on V-P discrepancies. Posterior lesions, especially in the right hemisphere, are more likely than frontal lesions to yield predictable profiles. Comparisons of the Wechsler test performance of patients with temporal lobe epilepsy have been made before surgery (when they have documented, lateralized lesions) and following surgery (after the lobe with the lesion has been removed). V-P differences were in the predicted directions for the left- and right-lesion samples of patients with epilepsy, but these differences were larger following the surgical removal of the temporal lobe.

Acuteness versus chronicity of lesions has long been considered a key variable in determin ing the magnitude of V-P discrepancies; however, the major study on which generalizations were based (i.e., acute patients have larger V-P differences in the predicted direction than do chronic patients) failed to match the patient groups on any variables. A compilation of research on this topic suggests that acute patients with right-hemisphere lesions display larger V > P profiles than chronic patients with right lesions. However, the acuteness-chronicity variable may not be meaningful for left-lesion patients.

Gender differences have been reported in some studies but not others. The predicted patterns of low Verbal IQ for left-lesion patients and low Performance IQ for right-lesion patients seem to be more characteristic of male than female patients. The cause of these apparent gender differences has been attributed by McGlone to greater cerebral asymmetry for males; Inglis and Lawson attribute the gender difference to the application by females of verbal strategies to solve nonverbal problems. Several analyses of WAIS and WAIS-R data argue for McGlone's cerebral asymmetry hypothesis while others argue for the Inglis/Lawson verbal mediation hypothesis.

One well-designed study found ethnic differences in whether males with brain damage display the predicted V-P patterns; Caucasian patients tended to evidence the predicted IQ relationships more so than African American patients. The latter finding requires cross-validation with a newer sample and with a diversity of ethnic groups.

Age as a variable in brain damage research has usually been approached by comparing lesions in children versus adults. In comparison to unilateral lesions in adults, lateralized lesions in children are less likely to produce equivocal results that show predictable V-P discrepancies. Although the possible reasons for this age-related difference are many, and disagreements abound among experts in the field, few investigations have systematically examined the relationship of chronological age to the V-P discrepancies observed for patients with lateralized lesions. In one well-matched study of patients with general brain damage and controls, when IQs were compared, the older controls showed a tendency to perform better than younger controls on all IQs; also, the discrepancy between IQs of younger and older groups was even more pronounced in the patient sample.

Educational attainment relates systematically to the size of a person's WAIS-III V-P IQ discrepancy. Those with less than a high school education, on the average, score 1-2 points higher on the Performance Scale; those with college degrees or higher score 2 ยก2 to 4J4 points higher on the Verbal Scale. These relationships have important clinical implications for individual neuropsy-chological assessment, and provide valuable baserate data for interpreting the results of V-P analyses in neuropsychological research studies. When the samples of patients with left hemisphere lesions are grouped by their mean education level, the mean P > V profile that is predicted for patients with left lesions is about 67 points for samples averaging 10 years of education or less, but is smaller (about 1-4 points) for those with 11 or more years of schooling. For patients with right-hemisphere lesions, the expected V > P profile is about 7 to 11 points for patient samples averaging 12 or less years of schooling, but is only about 3 points for samples that averaged 1 or 2 years of college. In fact, the latter sample (the most educated) is the only education group that tended not to show the characteristic pattern for either lesion group.

This chapter also discussed the clinical issues pertaining to individual neuropsychological assessment (as opposed to interpretation of research findings for groups of patients). When evaluating V-P differences for individuals instead of groups, extreme caution must be exercised. What are large differences between groups of patients may not even be statistically significant for a given individual. In addition, individual interpretation demands understanding of clinical phenomena associated with lateralized lesions. For example, patients with left lesions prototypi-cally demonstrate a profound depression known as a catastrophic reaction, while patients with right lesions are more prone to euphoria or indifference. These opposite reactions are likely to affect the observed V-P discrepancy in different ways.

Other behavioral observations must also be considered when evaluating V-P differences. Fatigue, on the Wechsler-Bellevue or WAIS, for example, may have led to a depressed P-IQ because the six Verbal subtests are given first on those tests; the alternation of Verbal and Performance subtests on the WAIS-R and WAIS-III makes fatigue less of a problem for contemporary examiners' interpretation of V-P differences. Clinicians also need to understand sensory and attentional deficits associated with lesions in the left or right hemisphere to facilitate V-P analysis.

Chapter 9

Understanding And Treating Autism

Understanding And Treating Autism

Whenever a doctor informs the parents that their child is suffering with Autism, the first & foremost question that is thrown over him is - How did it happen? How did my child get this disease? Well, there is no definite answer to what are the exact causes of Autism.

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