RELATIONSHIPS AMONG WECHSLER INTELLIGENCE AND MEMORY SCALE QUOTIENTS IN ADULT CLOSED HEAD

INJURED PATIENTS GARY S. SOLOMON, ROGER L. GREENE A N D STEPHEN P. FARR

Texas Tech University

MARK P. KELLY

Vanderbilt University

Correlations and discrepancy scores (Full Scale IQ minus Memory Quotient) among Wechsler intelligence and memory quotients were assessed in a sam- ple of 126 closed head injured (CHI) adults. Results indicated a slight, generalized decrease in CHI patients’ mean level of performance. A signi- ficant correlation of .76 was obtained between patients’ IQ and MQ scores. Discrepancy scores were relatively smaller than those found in prior research and were influenced partially by the patient’s age and by time of testing post- injury. The relative magnitude of discrepancy scores found in CHI is dis- cussed in relationship to other groups of brain-injured patients.

Since their introduction into the armamentarium of psychological tests, the Wechsler Adult Intelligence Scale (WAIS; Wechsler, 1955) and the Wechsler Memory Scale (WMS; Wechsler, 1945) have become two of the most frequently utilized neuropsychological instruments for the clinical assessment of intellectual and mnemonic functions (Hartlage & Telzrow, 1980). The global measures yielded by these tests, IQ (intelligence Quotient) and MQ (Memory Quotient), have been of diagnostic value in classifying a patient’s level of performance for these higher order cognitive functions. Furthermore, the rela- tionships (i.e., correlation and discrepancy) between IQ and MQ scores have received considerable attention over the years as an index of neuropsychological integrity.

Table 1 IQ-MQ Correlations

Study Subjects Age ?

MacCara (1953) Normals with superior IQs Fields (1971) 126 brain-damaged veterans 19-65 .83

Libb & Coleman (1971) 30 mixed rehabilitation center patients 16-56 .80

Black (1973) 50 head injured patients M = 21.4 .75

patients M = 47.7 .82

Ivinskis et al. (1971) 30 older children & 44 adolescents 10-14 & 16-18 .44 to .56

Kear-Colwell (1973) 66 neurological & 184 psychiatric

aAll correlations are statistically significant, p .05 (or greater).

This article is based in part on a dissertation submitted by the senior author to the Department of Psychology, Texas Tech University. Appreciation is extended to Drs. Russell L. Adarns, Nancy Adams, and Robert L. Kane for their facilitation of the data collection, and to Robin Hale-Fiske for her assistance with the data analysis. The influence and work of Dr. George P. Prigatano also are acknowledged. Appreciation is extended to Selena Cunningham for preparing the manuscript.

Drs. Solomon and Kelly also are affiliated with Rebirth, an organization for brain-injured persons and their families.

Requests for reprints may be addressed to Mark P. Kelly, Department of Psychiatry, Vanderbilt Univer- sity, Nashville, Tennessee 37232.

318

Wechsler Quotients in Head Injured Patients 319

Correlations between IQ and MQ scores have been the topic of considerable research. Table 1 presents an overview of studies that reported IQ-MQ correlations. Taken together, these studies led Prigatano (1978) to conclude, “Brain-damaged patients, mentally retarded patients, and normals who have IQs that do not exceed average limits show a high correlation between MQ and Full Scale IQ” (p. 9).

In constructing the WMS, Wechsler (1945) computed age correction scores that allowed for the MQ to be essentially comparable to the IQ. This procedure allowed clini- cians to assess memory deficits relative to a patient’s overall level of cognitive function- ing. Thus, the discrepancy between a patient’s MQ and IQ can be a useful index in assess- ing general neuropsychological intactness. MacCara (1 953) first raised the question of the amount of discrepancy between MQ and IQ needed to suggest organic memory im- pairment. Prigatano (1978) refined the question further by adding, “and in what type of patients?” (p. 10). Quadfasel and Pruyser (1955) reported a mean discrepancy score (IQ minus MQ) of 13.6 points in 19 epileptic male veterans with manifest focal abnor- malities, and a mean discrepancy score of 4.1 points in 19 matched patients whose EEG records revealed generalized abnormalities. Quadfasel and Pruyser operationalized a clinical memory deficit on the basis of an MQ that was 1 1 or more points below the IQ. Milner (1975), in her work with left temporal lobe seizure patients, concluded that a difference of 12 or more points between the IQ and MQ was indicative of a verbal memory deficit.

Prigatano ( 1 974) studied 15 head injury patients who had been rendered comatose and found a mean discrepancy score of 10.07 points, which differed significantly from the mean score of psychiatric controls. Zaidel and Sperry (1974) reported IQ and MQ data on 8 complete and 2 partial commissurotomy patients and found a discrepancy score of 12 or more points in all instances. Thus, in many cases, IQ-MQ discrepancy scores have been valuable in the psychometric identification of organically impaired patients.

The present study was concerned with MQ-IQ correlations and discrepancy scores among a group of adult closed head injury (CHI) patients. CHI, according to the Na- tional Head Injury Foundation (NHIF), has become “a national epidemic.” Dikmen and Reitan (1977) estimated the incidence of head injury in the U.S. to vary between 750,000 to 3 million per year, while NHIF estimates that over 700,000 persons yearly have head injuries severe enough to warrant hospitalization. Because the neurobehavioral sequelae of CHI (Levin, Benton, & Grossman, 1982) tend to persist well past the resolu- tion of immediate medical concerns (i.e., hematoma, raised intracranial pressure, hypox- iahchemia, skull fracture, etc.), descriptive psychometric data may be of benefit in assisting neuropsychologists with the identification of such deficits. The pathophysiology of CHI and the resultant diffuse structural damage have been described elsewhere (Jen- nett & Teasdale, 1981; Ommaya & Gennarelli, 1974).

METHOD Subjects

Participants in this retrospective investigation were patients diagnosed as suffering from CHI selected from the files of the following facilities: Psychology Clinic, Texas Tech University; Department of Psychiatry, Health Sciences Center, Texas Tech Univer- sity; Veterans Administration Medical Center, Oklahoma City; and Department of Psychiatry and Behavioral Sciences, School of Medicine, University of Oklahoma. Pa- tients of both sexes, of all racial/ethnic groups, and who spoke English as their primary language were considered for inclusion.

Patients’ ages ranged from 16 to 50 years. Younger patients were excluded because of their heightened cortical plasticity and better new learning skills (Brooks, 1972). Pa-

320 Journal of Clinical Psychology, March 1986, Vol. 42, No. 2

tients older than 50 years were excluded because of their reduced cortical plasticity (McGeer, Eccles, & McGeer, 1978), the increased probability of confounding with demen- tia (American Psychiatric Association, 1980), and- the substantial decline in cerebral vascular integrity that tends to occur at this point (Reitan, 1955).

Any patient with a history of previous CNS disorder, diagnosed substance abuse, mental retardation, psychiatric disorder, or prior head injury was excluded from par- ticipation. Patients who manifested specific focal neurological symptoms (e.g., visual field defect, hemiparesis, aphasic disorder) that would interfere with their ability to submit to testing also were excluded from consideration.

Procedure The availability of WAIS and WMS data was the final requirement for inclusion.

Over 2,000 clinical files were searched systematically; a total of 126 patients met the criteria for inclusion and served as subjects in the study.

Descriptive statistics for the patients are presented in Table 2. Of the 126 patients studied, 107 (84.9%) were male. Patients were referred for neuropsychological assess- ment anywhere from 2 weeks to 30 years post-injury (median = 30 weeks).

Table 2 Descriptive Statistics for Adult Closed Head Injury Patients"

M SD

Ageb Educationb Time Post-injuryc FSIQ

VIQ PIQ MQ Discrepancy score

30.27 11.87

123.57 93.85 94.98 92.82 90.71

3.14

11.61 2.83

237.55 16.33 17.46 15.28 20.12 12.64

aN = 126. byears. 'weeks. Note. -FSlQ = Full Scale IQ. VIQ = Verbal IQ. PIQ =

Performance IQ. MQ = Memory Quotient.

RESULTS Means and standard deviations for all Wechsler indices and for various patient

characteristics are presented in Table 2. The difference between the VIQ and PIQ means, although relatively small, was statistically significant, t(125) = 2.24, p -c .03. The mean discrepancy score (FSIQ minus MQ) also was statistically significant, t(124) = 2.88, p < .01. Intercorrelations among the various Wechsler indices are presented in Table 3.

Considerable variation in patients' discrepancy scores was noted, evidenced by the relatively large standard deviation. Correlational analyses were performed in order to identify possible moderator variable effects. Education level was unrelated to discrepancy scores (r = . l 1 , p >.lo), but patient's age (r = .17, p < .03) and time of testing post-

Wechsler Quotients in Head Injured Patients 32 1

injury (r = .23, p < .004) were correlated slightly and significantly with discrepancy scores. Furthermore, the correlation between discrepancy scores and MQ was moderate and significant (r = - .56, p < .0001). None of the Wechsler IQ indices was correlated significantly with discrepancy scores.

Table 3 Intercorrelation? Bet ween Wechsler Intelligence and Memory Scale Quotientsb

FSIQC .76 VIQC .74 .95 PIQE .67 .89 .I1

“All correlations are statistically significant, p < .001. bN = 126. ‘FSIQ = Full Scale IQ. VIQ = Verbal IQ. PIQ = Performance

IQ. MQ = Memory Quotient.

DISCUSSION Level of Performance

CHI patients obtained average WAIS and WMS scores that were, respectively, 6.15 and 9.29 points lower than expected mean performances. In terms of mean level of per- formance, CHI apparently affected WMS scores to a slightly greater extent than WAIS scores. The slight, generalized decline in CHI patients’ mean level of performance may be the psychometric reflection of the effects of mild, diffuse cerebral dysfunction. These comments should be viewed tentatively, in light of the absence of a control group of nonimpaired persons with whom statistical comparisons can be made.

Wechsler Correlations The overall pattern of intercorrelations among CHI patients’ WAIS scores was

remarkably similar to the patterns noted in Wechsler’s (1955, 1981) normative samples. The .76 correlation between CHI patients’ IQ and MQ scores indicated that: (a)

CHI patients’ IQ and MQ scores correlate highly, as noted with other brain-damaged groups (Prigatano, 1978); and (b) a high degree of common or shared variance exists between the tests in this group of patients. In fact, approximately 58% of the variance in one set of scores was accounted for solely on the basis of the other set of scores. This result offers partial support for the contention that IQ can be predicted on the basis of MQ (Fields, 1971).

Discrepancy Scores CHI patients’ mean discrepancy score was 3.14 points (SD = 12.64). Caution should

be taken in concluding that the lack of a large discrepancy score among CHI patients was indicative of neuropsychological intactness because virtually all CHI patients in this study were referred for neuropsychological assessment due to concerns (either on the part of the patient or physician) with regard to neuropsychological integrity in general, and memory dysfunction in particular. The CHI patients’ average discrepancy score was considerably smaller than that reported by Prigatano (1974), who found a 10-point discrepancy. The difference in size of discrepancy scores might well be a function of

322 Journal of Clinical Psychology, March 1986, Vol. 42, No. 2

sample size because the current investigation included almost nine times as many pa- tients as Prigatano’s initial pilot sample, and, thus, it yielded more reliable data.

Correlations between discrepancy scores and particular moderator variables (i.e., patient age and time of testing post-injury) suggested that larger discrepancy scores were noted in older patients and in those who experienced longer time intervals between in- jury and neuropsychological assessment.

The CHI patients’ mean discrepancy score also was considerably smaller than those reported previously for other groups of brain-damaged patients (Bornstein, 1982; Milner, 1975; Quadfasel & Pruyser, 1955; Zaidel & Sperry, 1974). It is interesting to note that mean discrepancy scores of 1 1 points or higher have been reported in patients with focal seizure abnormalities (Quadfasel & Pruyser, 1955), temporal lobe seizures (Milner, 1975), and commissurotomy (Zaidel & Sperry, 1974). Bornstein (1982) studied groups of unilateral lesion patients of mixed etiology, but most had strokes; mean discrepancy scores in the right and left hemisphere lesion groups were 8.3 and 9.8, respectively. Mean discrepancy scores of 5 points or less have been found in patients with generalized seizure abnormalities (Quadfasel & Pruyser, 1955) and in the current sample of CHI patients. One striking difference appears noteworthy: When the nature of the disorder is focal, large discrepancy scores have been found; conversely, when the nature of the abnormality is diffuse, or generalized, small discrepancy scores have been obtained. Although this hypothesis is speculative, it may be worthy of further research in understanding discrep- ancy scores in various patient populations.

REFERENCES AMERICAN PSYCHIATRIC ASSOCIATION. (1980). Diagnostic and Statistical Manual of Mental Disorders (3rd

BLACK, F. W. (1973). Cognitive and memory performance in subjects with damage secondary to penetrating

BORNSTEIN, R. (1982). Effects of unilateral lesions on the Wechsler Memory Scale. Journal of Clinical

BROOKS, D. N. (1972). Memory and head injury. Journal of Nervous and Mental Disease, 155, 350-355. DIKMEN, S., & REITAN, R. M. (1977). Emotional sequelae of head injury. Annals of Neurology, 2, 492-494. FIELDS, F. R. J. (1971). Relative effects of brain damage on the Wechsler memory and intelligence quo-

HARTLACE, L. C., & TELZROW, C. F. (1980). The practice of clinical neuropsychology in the U.S. Clinical

IVINSKIS, A., ALLEN, S., & SHAW, E. (1971). An extension of Wechsler Memory Scale norms in lower age

JENNETT, B., & TEASDALE, G . (1981). KEAR-COLWELL, J. J. (1973). The structure of the Wechsler Memory Scale and its relationship to “brain

damage.” British Journal of Social and Clinical Psychology, 12, 384-392. LEVIN, H. S., BENTON, A. L., & GROSSMAN, R. G . (1982). Neurobehavioral consequences of closed head

injury. New York: Oxford. LIBB, J. W., & COLEMAN, J. M. (1971). Correlations between the WAIS and Revised Beta, Wechsler Memory

Scale, and Quick Test in a vocational rehabilitation center. Psychological Reports, 29, 863-865. MACCARA, E. (1953). The Wechsler Memory Scale with average and superior normal adults. Bulletin of

the Maritime Psychology Association, 3 , 30-33. MCGEER, P. L., ECCLES, J. C., & MCGEER, E. G . (1978). Molecular neurobiology of themammalian brain.

New York: Plenum. MILNER, B. (1975). Hemisphere specialization: Scope and limits. In F. 0. Schmitt & F. G. Warden (Eds.),

The neurosciences: Third study program. Cambridge: MIT Press. OMMAYA, A. K., 8r GENNARELLI, T. A. (1974). Cerebral concussion and traumatic unconsciousness. Brain,

PRIGATANO, G . P . (1974). Memory deficit in head injury patients. Paper presented at the meeting of the

ed.). Washington: Author.

missile wound and closed head injury. Journal of Clinical Psychology, 29, 441-442.

Psychology, 38, 389-392.

tients. Diseases of the Nervous System, 32, 673-675.

Neuropsychology, 2, 200-202.

groups. Journal of Clinical Psychology, 27, 354-357. Management of head injuries. Philadelphia: Davis.

97, 633-654.

Southwestern Psychological Association, El Paso.

Wechsler Quotients in Head Injured Patients 323

PRIGATANO, G. P. (1978).

QUADPASEL, A. F., & PRWSER, P. W. (1955).

REITAN, R. M. (1955).

WECHSLER, D. (1945). WECHSLER, D. (1955). WECHSLER, D. (1981). ZAIDEL, D., & SPERRY, R. W. (1974).

Wechsler Memory Scale: A selective review of the literature. Archives of rhe

Cognitive deficit in patients with psychomotor epilepsy. Epilepsia,

The distribution according to age of a psychologic measure dependent upon organic

A standardized memory scale for clinical use. Journal of Psychology, 19, 87-95. Wechsler Adult Intelligence Scale. New York: Psychological Corporation. Wechsler Adult Intelligence Scale-Revised. New York: Psychological Corporation.

Memory impairment after commissurotomy in man. Brain, 97, 263-272.

Behavioral Sciences, 54.

4, 80-90.

brain functions. Journal of Gerontology, 10, 338-340.

WECHSLER MEMORY SCALE PERFORMANCE IN GEROPSYCHIATRIC PATIENTS

HARRY L. PIERSMA

Pine Rest Christian Hospital and

Michigan State University

Patients (N = 36) on a geropsychiatric acute care unit were administered the Wechsler Memory Scale (WMS) at admission and discharge. The results indicated that there were significant increases in WMS scores from admis- sion to discharge. Mean scores on the WMS were generally below those previously reported for normal geriatric groups, but above those reported for chronically ill or demented groups. As in previous studies, a significant positive relationship was found between education and WMS score, although no such relationship was found between age and WMS score. Overall, the results highlight the need for comprehensive norms for the elderly, which would increase greatly the practical utility of the WMS in clinical settings.

There are few tests that have been as frequently criticized yet as widely used as the Wechsler Memory Scale (Wechsler, 1945). Several review articles have summarized criticisms of the WMS with regard to basic psychometric issues such as standardiza- tion, norms, reliability and validity (Erickson & Scott, 1977; Prigatano, 1978). Criticisms of the standardization and norms have centered around the relatively small number of subjects and limited age range of the original normative sample. The WMS was normed on 200 individuals seen at Bellevue Hospital in New York. These individuals ranged in age from 25 to 50, although norms were extrapolated for older and younger age ranges. Wechsler had intended the original norms to be “provisional.” However, even today the norms are based upon the original standardization sample and have an upper age range of 60-64 years.

In recent years, there has been increasing interest in utilizing the WMS with elderly populations. Various researchers (Bak & Greene, 1980; Bigler, Steinman, & Newton, 1981; Brinkman, Largen, Gerganoff, & Pomara, 1983; Cauthen, 1977; Haaland, Linn, Hunt, & Goodwin, 1983; Hulicka, 1966; Klonoff & Kennedy, 1966; Margolis & Scialfa, 1984) have presented normative information on geriatric samples. The demographic and

Reprint requests should be addressed to the author at Pine Rest Christian Hospital, 6850 S. Division Ave., Grand Rapids, Michigan 49508.