Bimanual tactual discrimination in aging alcoholics.

Somesthesis and perceptual laterality were studied in normal aging and in aging alcoholic populations. The bimanual (dichhaptic) stimulation technique that was employed required participants to recognize and identify items traced onto the palms of both hands simultaneously, thereby eliciting competition for analysis by the two cerebral hemispheres. Performance of five groups of participants was compared (younger and older alcoholics and age-matched normal controls, and alcoholic Korsakoff patients); within each of the groups, the ability to identify verbal stimuli (letters) was compared with nonverbal stimuli (lines differing in orientation) for the right and the left hands separately. The results suggest that tactile discrimination accuracy for nonverbal information is disrupted by aging, but that alcoholism per se does not have this effect. The combined effects of alcohol abuse and aging were seen only on the tactual tasks that required identification of verbal items. Lateralization measures based upon performance by the two hands separately did not differentiate among the groups.