Dano A. Leli

Clinical detection of intellectual deterioration associated with brain damage

Leli and Filskov (1979) reported cross-validated classification accuracy that equalled 83% for a discriminant function derived on two measures of intellectual deterioration. This investigation made a preliminary assessment of the clinical utility of this function through a clinical-actuarial classification paradigm. Wechsler-Bellevue Intelligence Scale Form I protocols from 12 nonpsychotic nonimpaired and 12 cerebrally impaired individuals were used by experienced clinicians and predoctoral interns to identify the presence of intellectual deterioration associated with brain damage through their own clinical experience (Clinical Judgment condition) and, then, in conjunction with the discriminant function (Clinical-Actuarial condition). The classification accuracy from the discriminant function weights (Actuarial condition) and those from clinicians in the Clinical-Actuarial condition were statistically comparable and significantly above chance levels. These results indicate that the clinician who is assessing for the presence of intellectual deterioration associated with brain damage should rely heavily upon a valid actuarial index.

rCBF For Middle-Aged Males and Females During Right-Left Discrimination

rCBF was measured in 10 male and 10 female normal righthanders with an average age of 44.2 years. For the measures f1 and IS significant occipital lobe activation was produced bilaterally and for the measure IS significant left hemisphere parietal activation was produced also by a visually presented right-left discrimination cognitive activation task over and above the activation produced by a sensorimotor control task. The amount and pattern of blood flow changes were similar for both sexes. Performance of males on the cognitive task was not significantly better than that of females. However, an inverse relationship was found for males but not females between cognitive task performance and percentage increase in IS for all regions showing significant cognitive activation.

Focal changes in cerebral blood flow produced by a test of right-left discrimination☆

A sensorimotor control activation task was used to isolate the focal cerebral blood flow changes resulting from the visual and cognitive processing of a right-left discrimination task. Eleven normal right-handed males participated. The sensorimotor control task produced significant bilateral increases in flow in most cortical channels. Significant bilateral parieto-occipital activation was found for the right-left discrimination task over and above the flow changes produced by the sensorimotor control task. The left occipital flow increase resulting from the right-left discrimination task was found to be negatively related to task performance. An inverse relationship was also found between WAIS Performance IQ and the blood flow change in the left parietal channel. These results suggest areas for further testing concerning potential individual differences in cognitive processing during the performance of a right-left discrimination task.

Clinical-actuarial detection and description of brain impairment with the W-B form I

Assessed the clinical utility of four cross-validated discriminant functions derived on Wechsler-Bellevue (W-B) variables (Leli & Filskov, 1981) through a clinical-actuarial prediction paradigm. These functions were constructed to be actuarial indices of the presence, chronicity, extent, and lateralization of brain impairment. From W-B and demographic data gathered on brain-impaired and nonimpaired individuals, 6 students and 6 clinicians were asked to identify the presence and describe the nature of brain impairment with (Clinical-Actuarial condition) and without (Clinical Judgment condition) the four functions. Relative to the Clinical Judgment condition, Clinical-actuarial prediction was significantly better in identifying and determining the extent of brain impairment. Actuarial classification was significantly more superior in lateralizing deficits than were the other conditions. In both judgment conditions, students and clinicians did not differ significantly in classification accuracy. These results indicate that with actuarial indices, the adult Wechsler scales can be used accurately to identify and lateralize brain impairment.

Actuarial detection and description of brain impairment with the W‐B form I

In conjunction with other psychological tests, actuarial prediction studies have used the adult Wechsler scales to detect and describe the nature of brain impairment. However, the classification base rates from the independent use of the adult Wechsler scales have not been determined empirically. This investigation addressed this problem by assessing the ability of these scales to identify the presence, chronicity, extent, and lateralization of brain impairment through four cross-validated discriminant functions (N = 150). Hit rates from the function that differentiated nonpsychotic nonimpaired from brain-impaired Ss equalled 79%, while hit rates that equalled 75% were obtained from a function that compared right- from left-hemisphere lesioned Ss. Hit rates equalled 50% for the two functions that made acute vs. chronic and lateralized vs. diffusely impaired comparisons, respectively. In addition to cross-validating them on larger samples, it was recommended that the clinical utility of the functions be determined though a clinical-actuarial prediction paradigm.

Age effects on focal cerebral blood flow changes produced by a test of right-left discrimination.

The effects of age on focal cerebral blood flow changes resulting from the cognitive processing during right-left discrimination were examined. The pattern and amount of cortical flow were comparable for young and middle-aged subjects and consisted of flow increases in bilateral frontal, parietal and occipital regions. Task performance was negatively related to activation from left parietal and occipital channels. The frontal activation and the parietal correlation were attributed to the middle-aged subjects experiencing increased emotional arousal and attention to the right-left discrimination task due to hypothesized differences in cognitive effort and style, and/or novelty of formal examination situations.

Relevance of sensorimotor task components to the interpretation of task related blood flow changes

This study demonstrated the importance of documenting rCBF changes produced by the sensorimotor components of a cognitive task when making inferences regarding brain-behavior relations. Subjects were ten young, non-smoking adult, right-handed, normal male volunteers. They were administered two tasks having identical cognitive and similar sensory components but different response modalities (oral vs manual). The two tasks produced highly divergent rCBF landscapes. In conjunction with the results from a previous rCBF activation study, these data were used to illustrate the necessity of including sensorimotor control tasks in cognitive activation studies designed to elucidate brain-behavior relations.

Actuarial Assessment of Wechsler Verbal-Performance Scale Differences as Signs of Lateralized Cerebral Impairment.

Long-standing clinical lore holds that a discrepancy between Wechsler-Bellevue (W-B) Verbal/Performance Scale weighted scores is a more sensitive sign of lateralized brain damage than a discrepancy between Verbal/Performance Scale IQ. To assess this question, two step-wise discriminant functions using W-B Verbal and Performance Scale weighted scores (Function 1) and IQs (Function 2) as independent variables were derived and cross-validated on right- and left-hemisphere-lesioned subjects. Cross-validation hit rates were statistically comparable though disappointingly low (Function 1–67%, Function 2–64 %). These results do not support the clinical lore which favors a weighted discrepancy score over an IQ-discrepancy as a sign of lateralized cerebral impairment.