Volumetric cat measures

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Volumetric Cat Measures and Neuropsychological Performance in Alzheimer's Disease

E. D. Bigler a; D. Hubler b; E. Turkheimer c; C. M. Cullum c; S. Paver c; R. Yeo d a Austin Neurological Clinic and University of Texas, b University of New Mexico, c University of Texas, d Boston VA Hospital, Online Publication Date: 01 January 1984 To cite this Article: Bigler, E. D., Hubler, D., Turkheimer, E., Cullum, C. M., Paver, S. and Yeo, R. (1984) 'Volumetric Cat Measures and Neuropsychological Performance in Alzheimer's Disease', International Journal of Neuroscience, 24:3, 291 - 294 To link to this article: DOI: 10.3109/00207458409089819 URL: http://dx.doi.org/10.3109/00207458409089819

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VOLUMETRIC CAT MEASURES AND NEUROPSYCHOLOGICAL PERFORMANCE IN ALZHEIMER’S DISEASE E. D. BIGLER Austin Neriro/ogical clinic and University of Texas

D. HUBLER University of New Mexico E. TURKHEIMER University of Texas C. M. CULLUM University of Texas S . PAVER University of Texas

and R. Y E 0 Boston VA Hospital (ReceivedDecember 28,1983)

The following measures were computer generated from CAT scans of 31 patients with degenerative disorder (Alzheimer’s type) : Brain surface a T a (BSA), Brain volume (BV), Ventricular surface area (VSA), Ventricular volume (VV), and an Atrophy Index determined by the B S A / d m . Left and right hemisphere measurements were also determined for BSA, BV, VSA and VV. All patients received a standard neuropsychological battery of tests. Correlational analyses were then undertaken between the various CAT scan measures and neuropsychological performance. Results indicate that VV and the Atrophy Index measures are the most sensitive for the detection of degenerative morphological brain changes in relationship to neuropsychological impairment in the degenerative patient.

Since the advent of computerized axial tomography (CAT), this technique has been utilized in numerous studies attempting to document the relationship between cerebral atrophy and/or ventricular enlargement with neuropsychological test performance in cases of cerebral degenerative disease (Bird, 1982: Drachman, et QI. 1982; Jernigan, et al. 1980; Kaszniak, et QI.1979; Naeser, et al. 1982; Perret & Birri, 1982; Wu, et al. 1981). The results of such research have yielded rather conflicting findings concerning this relationship. As Bird (1982) points out, the discrepancies with this research are likely attributable to unitary and incomplete measures. For example, a common method used to determine the degree of cerebral atrophy is in terms of sulci enlargement. Typically, the mean width of several of the large sulci in the vertex plane are taken. However, there may be little relationship between a singular sulcus measureAddress to whom correspondence should be sent: Erin D. Bigler, Ph. D., Austin Neurological Clinic, (51 2-458-61 21)

71 1-F West 38th Street, Austin, Texas 78705.

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ment, such as this, and size of other sulci. Similarly, the size of a single sulcus may not relate to overall presence or absence of cerebral atrophy (Bird, 1982). Another example is the common measurement of ventricular enlargement by taking the linear size of the widest aspect of the anterior horns in terms of a ratio between that measure and a linear skull-to-skull measurement in the same plane. Another ventricular measure that has been utilized is taking the largest width of the body of the lateral ventricle These types of ventricular measurements are only unidimensional and, again, may not relate to overall ventricular size, shape or volume or with the presence of sulci enlargement (Bird, 1982). We have sought to correct these problems by using total volumetric measures of the cerebrum and ventricular system in patients with degenerative disease. METHODS Volumetric measures were based on the methods outlined by Turkheimer, et af. (1983) and Yeo, et af. (1983). Accordingly, left hemisphere (LHV), right hemisphere (RHV), and total brain volume (TBV) were obtained with similar measures obtained of left, right and total ventricular volume (LVV, RVV and TVV, respectively). A total brain surface area (BSA) and a total ventricular area (VSA) were also obtained. An Atrophy Index was also calculated for each patient by taking the total BSA and dividing it by the square root of TBV. All patients received the following neuropsychological measures : Wechsler Adult Intelligence Scale, Wechsler Memory Scale, Reitan-Indiana Aphasia Screening Test, Reitan-Wove Sensory Perceptual Examination, and the Trail Making Test. Correlational analyses were utilized for data comparison. 31 patients comprised the subject sample for this study. All patients had suspect or confirmed degenerative disease of Alzheimer’s type. All had been independently evaluated by one of four board-certified neurologists who were blind concerning the study. Routine CT scanning was obtained on all patients. There were 17 males and 14 females. The mean age was 69.8 years.

RESULTS Means of the various neuropsychological measures and morphologic brain measures are presented in Tables I and 11. Age was controlled for throughout the correlational analyses. No significant deficit relationship was found between TBV, LHV and RHV for the various neuropsychologic measures. However, BSA measurements did show a significant negative correlation with PIQ and 4 of the 5 Performance subtests (PC, BD, PA and OA). No significant correlations were present for the other neuropsychological measures. VSA measures also showed a significant negative correlation with PIQ and all Performance subtests. TVV was also found to be negatively correlated with PIQ and all Performance subtests. Since TVV can be divided into right and left hemispheric volume measures, correlational studies comparing L W with RVV were also conducted. These results indicate significant RVV correlations, in the negative direction, with all PIQ measures. LVV analyses yielded no significant correlations. VSA was correlated negatively with all Performance scores in the total number of sensory-perceptual errors on the Reitan-Klove sensory perceptual examination. Atrophy Index measures showed no consistent relationship with any VIQ measures,


ALZHEIMER’S DISEASE & CAT-NEUROPSYCHOLOGICAL MEASURES

293

TABLE I Neuropsychological Test Results Mean 49.9 99.3 24.8 90.1 95.6

WAIS Verbal Raw Score Verbal IQ Score Performance Raw Score Performance IQ Score Full Scale IQ Score WMS Memory Quotient Logical Memory Digit Span Visual Memory Associate Learning

=82

= = = =

Finger Oscillation Right Left

5.5 8.9 3.4 8.6 36.0 32.7

Trail Making Test* A B

3.8 3.8

Reitan-Klove Sensory-Perceptual Examination Right Left

1.5 1 .o

Reitan-Indiana Aphasia Examination. Verbal Spatial

2.1 2.9

Scaled score based on the ratings established by Russell, Neuringer and Goldstein (Assessment of Brain Damage: A Neuropsychological Key Approach. New York: Wiley, ‘1970). TABLE 11 Morphologic Brain Measures Total Brain Volume Left hemisphere volume Right hemisphere volume

Mean 872.6 cc. 436.4 cc. 436.2 cc.

Total Ventricular Volume Left ventricular volume Right ventricular volume

66.6 cc. 34.3 cc. 32.4 cc.

Brain Surface Area Ventricular Surface Area

410.8 cm2 125.9 cmB

but significant negative correlations were found with PIQ (BD, PC and PA) and the Memory Quotient (MQ) on the Wechsler Memory Scale, with visual memory being the most significant. DISCUSSION The ventricular volume measurements and the Atrophy Index appear to be sensitive volumetric change measures of cerebral morphology in patients with degenerative


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disease, and such measurements are related to the degree of cognitive decline present. PIQ and MQ measures were the most sensitive measures of cognitive decline. None of the motor tests were consistently related to volumetric changes nor were the scores on aphasia screening. Brain surface area measurements alone were also found to show little relationship between degree of cognitive impairment and structural cerebral measurements. These results suggest potential clinical significance in developing critical volumetric values in the neuroradiographic evaluation of the CAT scan of the patient with potential degenerative disease. The interface of such neuroradiographic measures with neuropsychological testing may result in a powerful diagnostic tool for the assessment of the patient with potential degenerative disease. The implications of these findings will be fully elaborated. BIBLIOGRAPHY Bird, J. M. Computerized Tomography, Atrophy and Dementia: A. Review. Progress in A’eurobiology 1982, 19, 91-115.

Drachman, D. A., Fleming, P., & Glossner, G. The multidimensional assessment for dementia scales. In S . Corkin, et u/. (Eds.) Alzheimer’s disease: 1982. A report of progress (Aging Volume 19) New York: Raven Press. Jernigan, T. L., Zotz, L. M., Feinberg, I., & Fein, G. The measurement of cerebral atrophy in the aged by computed tomography. In L. W. Pool (Ed.) Aging in the 1980’s. 1980. Washington, D. C.: American Psychological Association. Kaszniak, A. N., Garron, D. C., Fox, J. H., Bergen, D. & Huckman, M. Cerebral astrophy, EEG slowing, age, education and cognitive fufictioning in suspected dementia. Neurology 1979, 29, 1273-1927.

Naeser, M. A., Albert, M. S., & Kleefield, J. New methods in the CT scan diagnosis of Alzheimer’s Disease: Examination of white and gray matter mean CT density numbers. In S . Corkin, et at. (Eds.) Alzheimer’s disease: A report of progress, 1982. (Aging Volume 19) New York: Raven Press. Perret, E. & Birri, R. Aging performance decrements, and differential cerebral involvement. In S . Corkin, ef a/. (Eds.) Afzheimer’sdisease: A report qfprogress, 1982. (Aging Volume 19) New York: Raven Press. Turkheimer, E., Yeo, R., & Bigler, E. D. Digital planimetry in APLSF. Behuvior Research Methods, in press. Wu, S., Schenkenberg, T., Wing, S. D., & Osborn, A. G. Cognitive correlates of diffuse cerebral atrophy determined by computer tomography. Neurology 1981,31,1180-1184. Yeo, R., Turkheimer, E., & Bigler. E. D. Computer analysis of lesion volume: reliability, utility and neuropsychological applications. Clinical Netrropsychology 1983,45 (abstract), 1983.