Gender specificity of resting anterior electroencephalographic asymmetry and defensiveness in the elderly

It has been reported that defensiveness in women is associated with relative left-frontal electroencephalogram (EEG) activation, while defensiveness in men is associated with relative right-frontal EEG activation. The present study examined whether this result generalized to men and women between the ages of 58 and 70.

The Marlowe-Crowne Social Desirability Scale (MCSD) and EEG testing were used to examine relationships between gender, defensiveness, and anterior asymmetry.

Men (n = 18) and women (n = 54) between the ages of 58 and 70 (mean age = 64.22, standard deviation = 3.003) were recruited from Tucson and surrounding areas of Pima County, Arizona. They were selected from among participants in an integrative health sciences study of aging that took place between 1991 and 1993.

Subjects were divided into high-defensive and low-defensive groups based on a median split on the MCSD. EEGs were recorded from 19 channels (standard 10-20 montage), referenced to linked ears, and digitalized on-line at 128 Hz (band pass 2-32 Hz) during consecutive 60-second eyes-open and eyes-closed baselines. Two-second epochs containing bioelectric artifacts > 50 microvolts were eliminated from analyses. Average alpha (8-13 Hz) power (microV2)) was computed by Fast Fourier Transform and natural log (ln) transformed for normalization. Asymmetry scores were computed (log[right]-log[left]) for F4-F3, Fp2-Fp1, F8-F7, C4-C3, T4-T3, T6-T5, P4-P3, and O2-O1 for aggregated eyes-open and eyes-closed baselines. R-L asymmetry scores were analyzed for the aggregate frontal lead pairs, as well as for each pair separately.

Findings were similar to those previously reported in that the direction of the relationship in men and women was the same. The results differed in that we found left-frontal activation in low-defensive men, whereas the previous study found right-frontal activation in high-defensive men. Furthermore, although in the same direction, the relationship for women was nonsignificant.

These differences may have been due to the age of the participants, a lax impedence criterion, or the use of the MCSD rather than the L scale of the Eysenck Personality Questionnaire, as in the earlier study. Nevertheless, the findings suggest that gender differences in the relationship between resting anterior EEG asymmetry and defensiveness may persist throughout the life span.