MEMORY ASSESSMENT USING THE STRUB-BLACK MENTAL STATUS EXAMINATION AND THE WECHSLER MEMORY SCALE

NANCY SIMPSON

Florida Institute of Techno logy

F. WILLIAM BLACK AND RICHARD L. STRUB

LSU Medical School

A systematic mental status exam often can differentiate accurately patients with organic brain disease from normal persons and those with functional disorders. The present study attempts to validate the memory portion of the Strub-Black Mental Status Exam by comparing it to the Wechsler Memory Scale. Twenty-five brain-damaged and 25 routine medical patients were given Form I of the Wechsler Memory Scale and the memory portion of the Strub-Black Mental Status Exam at their hospital bedside. Results indicate significant differences in almost all scores between the brain-damaged and normal groups on both the Wechsler Memory Scale and Mental Status exam; the Mental Status Exam differentiated between groups at a higher leve of significance of ANOVA and ANCOVA comparisons of total memory scores, as well as several subtests. In these samples, age, more than educa- tion, was an important factor that affected memory test performance. The Mental Status Examination appears valid for the differentiation of clinical samples and for the documentation of specific aspects of memory dysfunc- tion in individual brain-damaged patients. This study represents a begin- ning step in providing normative data on components of the Strub-Black mental status examination.

Memory is a highly complex psychological process that allows the active aquisition and storage of new information and the efficient recall of previously learned informa- tion. This basic, yet multi-step process includes at least the following separate aspects or functions: (1) reception or registration of information by a particular sensory modality (e.g., auditory, visual or tactile); (2) temporary holding in immediate or short-term memory; (3) storage or consolidation of the information into more permanent long- term memory; and (4) recall or retrieval of the stored information (Erickson & Scott, 1977; Strub & Black, 1977, 1985).

Deficits in recent memory or new learning ability are frequent findings in patients with a wide range of brain disorders and are often the first recognizable impairment in dementia. Clinically, it is important to note that memory may be impaired in pa- tients who demonstrate no obvious motor, sensory, language, or other cognitive deficits. Because of its importance as a symptom and sign of brain disease, it is essential that clinicians have the ability to assess the adequacy of memory functions. A valid evalua- tion allows the clinician to differentiate patients with organic disease from those with functional disorders and to establish the nature and degree of the memory deficit in those patients who do have such a disorder.

Tests of memory function range from the relatively gross and often cursory tests included in bedside mental status examinations to the formal standardized tests, such as the Wechsler Memory Scale and Randt Memory Test. There are also a variety of

All correspondence should be addressed to F. William Black, Ph.D., Department of Neurology, LSU Medical Center, 1542 Tulane Avenue, New Orleans, Louisiana 701 12.

147

148 Journal of Clinical Psychology, January 1986, Vol. 42, No. 1

highly sophisticated experimental techniques used to investigate various memory paradigms in patients with known specific memory deficits (e.g., Korsakoffs syndrome).

Because of clinical applicability, this paper will focus on a standard memory scale (the Wechsler Memory Scale; Wechsler, 1945) and a bedside mental status examination commonly employed by physicians (the Strub-Black Mental Status Examination; Strub & Black, 1977, 1985).

The Wechsler Memory Scale, one of the first attempts to objectify memory perform- ance, is a well known psychometric instrument that requires little detailed introduction here. Basically, the WMS is an attempt to quantify a range of cognitive functions, some of which are related to memory performance (e.g., mental control) and some of which are direct tests of specific aspects of memory and learning ability. Subtests included on the WMS are: (1) Personal and Current Information; (2) Orientation; (3) Mental Con- trol; (4) Logical Paragraph Recall; (5) Digit Repetition; (6) Visual Reproduction; and (7) Paired Associate Learning. A summary score that is corrected statistically for age, the Memory Quotient (MQ), reflects overall performance on the test. The WMS has been shown to differentiate reliably between normal and brain-injured or diseased samples when age and intellectual level are controlled. The problems implicit in the content and the psychometric properties of the WMS have been well documented elsewhere (Du- jovne & Levy, 1971; Erickson & Scott, 1977; etc.) and will not be reiterated here. Suffice it to say, despite its many shortcomings, the WMS remains one of the most frequently used clinical tests in the United States to date. Until the recent development of the Randt Memory Test (Randt, Brown, & Osbourne, 1980) and the Denman Neuropsychology Memory Scale (Denman, 1984), the WMS was the only standardized test of overall memory functioning available for general clinicaI use.

The mental status examination derived from the work of Strub and Black (Black & Strub, 1976; Strub & Black, 1977, 1985; Strub, Black, & Leventhal, 1979) is a set of clinical assessment procedures that are presented in a hierarchial fashion, from basic attentional and language functions to the higher cognitive functions of abstraction and the active manipulation of concepts. The components of the examination were selected from those bedside tests included in earlier neurological mental status examinations and certain neuropsychological procedures that have proven both reliable and clinically valid. The examination was developed to assess comprehensively, yet briefly, those mental func- tions that differentiate between normal and neurologically impaired patients, as well as to document the nature of the patient’s cognitive functioning. Memory testing is an important aspect of this examination, which contains specific tests of (1) digit repeti- tion; (2) orientation; (3) remote memory; (4) verbal learning and recall; ( 5 ) visual memory; and (6) paired associate learning.

The Strub-Black mental status examination has proven clinically useful and cur- rently is used widely both by physicians for bedside and office examinations and by psychologists to screen for those patients in need of a more comprehensive neuro- psychological evaluation. Its use thus far has been primarily clinical and qualitative. The present study represents one aspect of continuing efforts t o provide standardiza- tion and normative data needed to establish its psychometric properties and to validate its clinical utility.

The primary purposes of this study were to:

1 .

2.

Provide normative data on the memory components of the Strub-Black men- tal status exam;

Compare memory test data obtained from the mental status exam and the more psychometrically derived Wechsler Memory Scale in an effort to standardize the Mental Status Exam;

Memory Assessmen f 149

3 . Determine whether the mental status examination can differentiate adequately between brain-damaged patients and normals selected from a socially similar popula- tion; and

4. Determine the degree to which demographic factors, such as age and educa- tion, affect memory test performance, both on the Mental Status Examination and on the Wechsler Memory Scale.

METHOD Subjects

Subjects were 50 patients seen at LSU Medical Center and Charity Hospital, New Orleans. Twenty-five subjects were determined by independent criteria to be brain damaged, and 25 were hospitalized normal controls. The samples were composed largely of lower socioeconomic patients of limited education,, a group typical of those patients seen in large inner city public hospitals. This population provides the greatest challenge in differentiating patients with brain disease from low IQ normal patients (Strub et al., 1979) and was chosen purposely to test the utility of the Mental Status Exam under difficult clinical conditions.

Patients in the brain-damaged group had unequivocal diagnosed neurologic disease. The following classes of neurologic disorder were represented within the sample: Post- traumatic Encephalopathy (N = s), Cerebral Vascular Accident (N = 7), Alzheimer’s Dementia (N = 4), Subdural Hematoma (N = 4) and Other (N = 2). The clinical group was composed of 17 males and 8 females, with a mean age of 47 years (SD = 16.06) and a mean educational level of 8.8 years (SD = 3.59). All clinical patients were alert and fully capable of validly completing the test battery at bedside.

The control group consisted of medical patients selected from the same hospital population, with no known neurologic or psychiatric disease, who were hospitalized on the obstetric or orthopedic wards. No control patients were either acutely or systemically ill. Represented in the group were 12 males and 13 females, with a mean age of 30 (SD = 13.37) and a mean educational level of 10.6 years (SD = 2.12).

Procedure Subjects were administered the Wechsler Memory Scale (Form I) and the memory

portion of the Strub-Black Mental Status Examination (Strub & Black, 1977, 1985) at their hospital bedside. Wechsler’s scoring procedures were used to obtain an age-corrected Memory Quotient, as well as raw scores on each of seven subtests: Personal Informa- tion, Orientation, Mental Control, Memory Passage, Digit Span, Visual Reproduction and Paired Associate Learning. The memory portion of the Strub-Black Mental Status Exam also includes various subtests that measure immediate recall, orientation, remote memory, new learning ability, and visual memory. These subtests include Digit Span, Vigilance, Orientation, Personal Information, Historical Facts, Four Random Words, Paired Associate Learning, Verbal Recall of Paragraph Material, and Hidden Objects. Raw scores were obtained for each student, based upon the number of items completed correctly. (See Table 5 for a listing of all variables.) A total Mental Status Memory Score was obtained from the summed score on each of the subtests.

Statistics Individual patients’ scores on each subtest of the Wechsler Memory Scale and Strub-

Black Mental Status Exam were calculated and computer coded for data analysis. Pearson product-moment correlations were computed between the subscales of the two tests in both the brain-damaged and control groups. A one-way multivariate analysis of variance (MANOVA) was used to compare between sample scores on the two tests. One-way

150 Journal of Clinical Psychology, January 1986, Vol. 42, No. I

analysis of variance that compared demographic data between groups revealed a signi- ficant difference in age and education (Fs = 16.6 and 4.5, respectively). Accordingly, age and education were covaried using an analysis of covariance (ANCOVA) procedure between groups. Post hoc comparisons of individual subtest performance were conducted using univariate ANOVAs.

RESULTS A multivariate analysis of variance (MANOVA) that compared Wechsler Memory

Scale subtest scores between groups revealed a significant difference (F = 5.89, p < .001). Post hoc univariate ANOVAs were computed for all individual WMS subtests, which resulted in highly significant differences on each variable. See Table 1 for these data.

Table 1 Means, Standard Deviations, and F Tests for Between-sample Dixerences on the Weckler Memory Scale, Strub-Black Mental Status Exam, and Demographic Data

~ ~ ~~

Brain-damaged group Control group

Subscale M SD M SD F P

WMSl WMS2 WMS3 WMS4 WMS5 WMS6 WMS7

MQ MS 1

MS2 MS3

MS4 MS5

MS6 MS7 MS8 MS9 MSlO MSl l MS12 MS13 MS14 MS15

MS16 MS17 TOT

Age Education

3.5 3.2 2.3 2.1 7.8 1.8

5.2 63.6

4.2 10.2 8.7

2.6 2.7

3.4 3.4 1.3 1.5

1.9 1.8 1.3 2.8

1 .O

2.1

1.4 3.5

33.4 47.0

8.4

1.8 4.8 1.7 4.8 2.3 5.5

2.1 5.1 2.4 10.0

2.7 6.8 4.4 13.6

12.5 84.9

.9 4.8 15.3 .2 2.1 10.6

.7 3.0

.8 3.0 1.3 4.6 .9 3.9 .7 1.5

1.2 3.3

1.4 3.6 1.4 3.9 1.4 3.7 1.7 4.7

1 .o .2 1.2 3.0

I .5 3.0 2.5 6.0

10.9 50.0 16.1 30.0

3.5 10.6

1.1 .4

2.2

2.9 2.2

3.7 3.4

16.2

1.3 .6 .6

.o

.o

.6

.3

.7

.7

.7

.3 2.6

.7

.6

.7

1.1 1.4 5.4

13.4 2.1

9.5 24.6 25.0

17.5 12.3

30.6 55.4 27.3

3.6 10.9 20.2

8.0 3.1

19.3 7.9

.6 39.3 28.8 52.8 16.2 27.8

9.3 9.3

18.8 19.1 47.1 16.6 4.5

.oo3

.ooo

.Ooo

.ooo

.oo1

.Ooo

.Ooo

.Ooo

ns

.002

.Ooo

.oo7 ns

.Ooo

.oo7 ns

.Ooo

.Ooo

.Ooo

.Ooo

.Ooo

.oo4

.004

.ooo

.Ooo

.ow

.om

.038

Note.-See Table 5 for variable label names.

Memory Assessment 151

All differences were in the expected direction; the control group performed more adequately. Because both age and educational level are know to affect memory test per- formance, and differed significantly between the two groups, ANCOVAs with these variables covaried were computed. Again, all WMS subtests differed significantly in the two samples. See Table 2 for these data.

Table 2 F Tests for Between-sample DiTereences With Age and Education Covaried (ANCOVA)

WMSl WMS2 WMS3 WMS4 WMS5

WMS6

WMS7

MQ MS 1

MS2 MS3

MS4 MS5 MS6 MS7

MS8 MS9 MSlO MSl l MS12 MS13 MS14 MS15 MS16 MS17

TOT

5.42 12.27 13.82 9.57 5.75

23.30

28.20 10.66 1.93

5.51 13.29 1.53 3.44 8.41 3.11

3.18 9.93

15.07

20.35 10.84 9.43

3.05 12.58 9.73

15.56

28.00

.008

.Ooo

.Ooo

.Ooo

.006

,000 .Ooo

.Ooo

ns ,007 .Ooo

.001

.041

.001 ns ns

,001

.Ooo

.Ooo

.Ooo

.Ooo

ns .ooo .Ooo

.Ooo

.Ooo

A second MANOVA was attempted to compare Mental Status subtest scores be- tween groups, but could not be computer analyzed because of the subject/variabIe ratio and linearly dependent variables. Notwithstanding this statistical limitation, further analyses of individual Mental Status subtest performance in the two samples (multiple ANOVAs) revealed significant differences on all measures except Digit Span, Orienta- tion to Place, and Historical Facts. (See Table l . ) Very limited variance in the scores on these variables undoubtedly accounted for the lack of significant differences. AN-

152 Journal of Clinical Psychology, January 1986, Vol. 42, No. I

COVAs (age and education covaried) revealed significant between-group differences on 13 of 17 Mental Status variables. (See Table 2.) Only Digit Span, Personal Informa- tion, Historical Facts, and Hidden Objects Named But Not Found failed to differen- tiate significantly between the two groups.

Correlations between the subtests of the two instruments, Wechsler Memory Scale and Mental Status Examination, appear in Tables 3 and 4.

Table 3 Correlations Between Wechsler Memory Scale and Strub-Black Mental Status Exam Memory Tests in Normal Patients

WMSl WMS2 WMS3 WMS4 WMS5 WMS6 WMS7 MQ

MS1 MS2 MS3

MS4 MS5 MS6

MS7 MS8 MS9 MSlO MSl l MS12

MS13 MS14

MS15 MS16

MS17 TOT

.09 - .09

.09 - -

.09

.39*

.39

.06

.32 - .04

.35*

.24

.24

.24

.20

.28

.40*

.I1

.13

.27 - -

.21 - .16 - .01 - .13

.04 - .13 - .01 - .19

.18 - .18

.10

.01

.I1

.27 - .27

.16 - -

.16

.08

.38*

.14

.27 - .07

.61**

.01

- .03 .47** ,551'

.69**

.67**

.53** -.11

- .03 - -

- .06

.23

.30

.22

.40* - .02

.64**

.25

- .24 .59** .32 .56** .75**

.59** - .34*

- .08 - -

- .08 - .05

.24

.22

.30

.07

.45*

.35*

- .32 .46* .17

.31*

.49**

.54** - . I5 - .03 - -

- .03

.05 - .04 - .08

.12 - .01

.37*

.06 -.11

.29

.35*

.43*

.45*

.27 .54** - .03 - .26

.26 .14 - - - -

.26 . I4 - .14 .08

.39* .39*

.19 .10

.39* .38*

.05 .07

.62** .71**

.02 .19

. 00 .11

.45* .62**

.39* .34

.55** .60**

.63** .76** ~

Note. -Correlation cannot be computed. *p <.05. **p <.01.

As expected, a preponderance of correlations were significant in both the normal and brain-damaged samples. Far more correlations were significant at a higher level of significance in the brain-damaged group. Within a patient group, the two tests appear to be related consistently (total Mental Status score and WMS MQ: r = -79, p < .001). Somewhat unexpectedly, the WMS Orientation subtest failed to correlate significantly with any Wechsler or Mental Status variable, due largely to the very limited range of scores produced by normals on this variable.

DISCUSSION The multivariate analysis of variance performed on the Wechsler Memory Scale

provides further support for the clinical utility of this test in discriminating between groups of normal and neurologically impaired subjects. The subtests of Orientation, Mental Control, Visual Reproduction, and Paired Associate Learning, as well as the Memory Quotient, were particularly effective in distinguishing between the two groups.

Memory Assessment 153

Table 4 Correlations Between Wechsler Memory Scale and Strub-Black Mental Status Exam Memory Tests in Brain-damaged Patients

WMSl WMS2 WMS3 WMS4 WMS5 WMS6 WMSI MQ

MS 1 MS2 - MS3 MS4 MS5 MS6

MSI MS8 MS9

MSlO MSl l

MS12

MS13 MS14

MS15 MS16 MS17

TOT

. l l .03

.42* -.49** -

.49** .69**

.53** .38*

.34* .58**

.28 .54

.06 .57**

.12 .02

.49** .54**

.56** .77**

.64** .go**

.41* .34*

.53** .lo**

.06 .01

.62** .lo**

.60** .51**

.66** .66**

.67** .84**

.41** ' .06

.26

.31

.23

. l l

.24

.29

.38*

.50**

.46**

.32

.03

.24

.41**

.37*

.45*

.48**

.10 - .49**

.50**

.34*

.38*

.31*

.31 - .12

.33

.51**

.50**

.62**

.75** - .31

.66** .81** .82** .16**

.49* - .18

.39*

.21

.31*

.25

.58**

.38*

.27

.53**

.41**

.39*

.14

.20 .59**

.39*

.52**

.56**

- .19

- .06 .54** .34* .24 .52** .41*

.16

.58**

.53**

.61**

.22

.40* - .20

.51**

.33

.45**

.57**

.23 - .33

.63**

.46**

.44*

.48**

.51**

.02

.52**

.14**

.72**

.52**

.71** - .21

.79**

.69**

.80**

.87**

.36* - .28

.41*

.34

.34*

.34

.51**

.22

.51**

.14**

.65**

.43**

.51** - .02

.61**

. I0

.75**

.19**

* p < .05. **p < .01.

Interestingly, Visual Reproduction and Paired Associate Learning actually discriminated at a somewhat higher level than did the MQ. In sum, neurological patients perform significantly less adequately than normals of a similar social background on the Wechsler Memory Scale and very significantly less adequately on several of the subtests.

The MANOVA attempted with the Mental Status subtest scores could not be com- puted because of the subjecthariable ratio and linearly dependent variables. Univariate ANOVAs were computed between samples for the 18 Mental Status variables. All variables differed significantly in the two groups, with the exception of Digit Span, Orien- tation to Place, and Historical Facts. Performance on the former two subtests genuinely did not differ appreciably in the two samples, while the format of Historical Facts (only two questions) reduced the possibility of discrepant performance. Of the Mental Status variables, the best discriminators were 4 Words recalled after 30 minutes, the total of all memory scores, 4 Words recalled after 5 minutes, and 4 Words recalled after 10 minutes. Accordingly, the memory subtests from the Mental Status Exam tend to discriminate between normals and neurological patients as adequately as the WMS.

As it is known that age and education (as well as intelligence and other variables) are correlated with memory test performance, it is important to consider such factors when one is evaluating memory in clinical settings. With both age and education covaried, all Wechsler Memory Scale subtests significantly discriminated between groups. Of the Mental Status variables, only Digit Span, Personal Information, Historical Facts, and Hidden Objects Named But Not Found failed to reach statistical significance. The two

154 Journal of Clinical Psychology, January 1986, Vol. 42, No. 1

Table 5 Variable Labels _ _ ~

WMSl WMS2 WMS3

WMS4 WMSS WMS6 WMS7 WMSS

Wechsler Memory Scale

Personal Information

Orientation Mental Control Memory Passages

Digit Span Visual Reproduction

Paired Associate Learning Memory Quotient

Mental Status Exam

MSl

MS2 MS3 MS4 MS5

MS6 MS7

MS8 MS9

Digit Span V i g i 1 an c e Orientation Total Person

Place Time Personal Information Historical Facts 4 Words-5 Min

MSlO MSll MS12 MS13 MS14

MS15 MS16 MS17 TOT

4 Words-10 Min 4 Words-30 Min

Hidden Objects Objects Found

Named not Found

Easy Paired Associates Difficult Paired Associates

Total Paired Associates Total Mental Status score

simple subtests of word recall and paired associate learning are particularly effective in dichotomizing brain-injured and normal hospital controls. Thus, both the WMS and the memory subtests of the Mental Status Exam appear clinically useful in assessing patients of various ages and levels of education. This is true for comparing patient samples and for the purpose of documenting the nature of the memory deficit in individual patients.

Correlational matrices of Mental Status variables and Wechsler Memory Scale subtests were computed in both normal and brain-damaged groups. As expected in two tests designed to measure similar functions (i.e., aspects of memory), there were multi- ple significant correlations in both samples. There were both more and higher-level cor- relations in the brain-damaged group, probably due to the wider range of performance within this sample. The two tests do, in fact, appear to assess very similar functions, although in somewhat different ways.

SUMMARY These results demonstrate the clinical utility of both the Strub-Black Mental Status

Exam and the Wechsler Memory Scale in discriminating between normal and brain- damaged groups. Both procedures seem sufficiently valid to provide accurate descrip- tions of relative levels of performance on various aspects of memory functioning in in- dividual patients. The Wechsler Memory Scale has been used extensively since its incep- tion to document the memory deficits in patients suspected of having neurologic condi- tions. This paper has attempted to provide comparative and normative data for the Strub- Black Mental Status Exam, so that it can be used with confidence in the documentation

Memory Assessment 155

of similar disorders. The results of this preliminary study suggest that the memory com- ponents of the Mental Status can be used validly for this purpose. Further research is needed with regard to the use of the test with individual patients. The next step in ob- jectifying the Mental Status will require addressing its other components and the establish- ment of cutting points to allow maximal correct patient classification with minimal false positive and false negative categorization.

This study is a beginning in providing normative data on the Mental Status Exam, starting with the memory components. When compared with the WMS, the tests are very similar and yield high correlations among subtests. The Mental Status Exam ac- tually differentiated at a higher level of significance on both the ANOVA and ANCOVA comparisons of Wechsler Memory Scale MQ and Mental Status Total Memory Score. In these samples, age, more than education, was an important factor that adversely affected memory test performance.

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of Clinical Psychology, 27, 331-354. ERICKSON, R. C. , & SCOTT, M. L. (1977). Clinical memory testing: A review. Psychological Bulletin, 84,

RANDT, C. T., BROWN, E. R., & OSBOURNE, D. P. (1980). A memory test for longitudinal measurement

STRUB, R. L. , & BLACK, F. W. (1977, 1985). The mental status examination in neurology. Philadelphia:

STRUB, R. L., BLACK, F. W., & LEVENTHAL, B. (1979). The clinical utility of reproduction drawing tests

WECHSLER, D. (1945). A standardized memory scale for clinical use. Journal of Psychology, 19, 87-95.

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