NEUROPSYCHOLOGICAL PERFORMANCES OF MALE AND FEMALE SUBJECTS WITH UNILATERAL CEREBRAL LESIONS.

Abstract

Male-female differences in neuropsychological functioning and whether there exists a differential cerebral lateralization between sexes has recently received much attention in the literature. Further research is needed because much of this literature has been plagued by poor experimental design and statistical analyses, and reliance upon measures with little practical significance. The current experiment addresses the question of whether male and female adults with unilateral cerebral lesions have differing neuropsychological profiles and whether these profiles support the hypothesis of differential cerebral lateralization. Subjects were adults with independent neurological evidence of either no brain damage or a unilateral cerebral lesion of either neoplastic or vascular origin. There were 48 with right hemisphere damage, 48 with left hemisphere damage and 28 controls. Each group had equal numbers of males and females, for a total of six sub-groups. The distribution of age, education, lesion locus and severity, and handedness was controlled for all groups. Subjects were administered the Halstead-Reitan Neuropsychological Test Battery for Adults. The measures from the Halstead-Reitan Battery were divided into groups of variables representing major aspects of neuropsychological functioning. Results for each variable grouping were subjected to multivariate analysis of variance and appropriate post-hoc procedures. Intra-individual patterns of lateralization (Verbal I.Q.-Performance I.Q. differences) were also examined. Contrary to previous reports, the results failed to produce evidence of a differential lateralization of cognitive functions between sexes. Also, the intra-individual patterns of lateralization showed similar patterns among males and females with unilateral cerebral lesions, although the magnitude of the VIQ-PIQ differences were smaller for females than for males. Several significant sex differences consistent with earlier research were found. Of these, a slight female advantage was found on the Digit Symbol test as well as Tactile Finger Recognition of the right hand. Males performed better than females on Finger Oscillation with the dominant hand and made fewer mistakes in reporting on double simultaneous stimulations. It was concluded that although small differences in neuropsychological functions do exist between sexes, they do not reflect major differences in cerebral organization or overall higher cognitive abilities.