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January2005 Vol.42 Issue:        1        Table of Contents
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Neuropsychological Performance in Normal Adults In Relation to Clinical Variables and Regional Brain Perfusion

Mahmoud Allam1, Fadya Elwan2, Manal S. Fahmy1, Ebtesam Fahmy1, Hosna Mostafa3, Nervana El-Faioumy1, Noha Abo-Krysha1, Jehan Ramzy1
Departments of Neurology1, Psychology2, Nuclear Medicine3, Cairo University


Objective: Mainly to characterize changes in neuropsychological performance and regional brain perfusion at single photon emission computed tomography (SPECT) associated with normal aging, gender, education and cerebrovascular risk factors and to consider SPECT findings as predictors of performance on psychometric tests. Methodology: Neuropsychological testing and perfusion SPECT images using 99mTc-hexamethyl propyleneamine oxime (HMPAO) were obtained from 48 normal subjects (16 men, 32 women) aged 21-84 yrs. Results: Advancing age, after adjusting for gender, vascular risk factors and education,  was associated with poorer performance on tests for fluid analytical abilities, executive functions, speed of information processing, attention, visuospatial and constructional abilities but not with crystallized abilities. Women did better on incidental (verbal short-term) memory tests compared to men. Education was a strong predictor of increased scores on nearly all psychometric tests except for incidental memory; whereas vascular risk factors were associated with only executive functions. Multiple regression analyses demonstrated an age-related regional decline in right frontal, bilateral parietal, and occipital lobes. Women had higher perfusion than men in all regions of interest except bilateral temporal lobes. Vascular risk factors accounted for a significant proportion of variance in average cerebral perfusion of left temporal, right thalamus and bilateral basal ganglia regions, all of which were not influenced by advancing age. Increased average perfusion of right frontal region was a significant predictor of  better performance on tests of fluid analytic abilities (abstract/spatial reasoning), visuospatial and constructional abilities, whereas increased perfusion of left frontal region was a significant predictor of  better performance on tests of executive functions mainly speed of information processing and perceptual mental state as well as crystallized abilities (similarities). Increased perfusion of right occipital region was a significant predictor of  better performance on tests for intentional (sensory) memory; while  increased perfusion of right parietal and right thalamic regions was a significant predictor of  better performance on tests for incidental (verbal short-term) memory. On the other hand decreased perfusion of left occipital region was a significant predictor of improving performance on tests of executive function. In addition, decreased perfusion of left parietal region was a significant predictor of better performance on tests of crystallized abilities (intentional memory and similarities) and block design. Relative decrease of cerebral perfusion in other regions in association with better performance of psychometric tests was attributed to either a compensatory mechanism or a lack of inhibition or task-induced deactivation that occurs at younger years and leads to reduced resting metabolic activity with advancing age. Conclusion: Performance on psychometric tests is associated with activation of a distributed network of brain regions which varies with advancing age. The recognition of functional imaging correlates to changes in cognitive function is important in enabling the distinction to be made between age- and dementia-related abnormalities, especially that functional abnormalities may be detected earlier.

(Egypt J. Neurol. Psychiat. Neurosurg., 2005, 42(1): 115-135).


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