Dichotic asymmetries in aging and alcoholic subjects.

It has been suggested that certain cognitive changes found both with aging and with chronic alcoholism are accompanied by alterations in hemispheric functional asymmetries. One prevalent view states that these well-delineated cognitive changes are directly related to a selective disruption of right hemisphere function. The present study tested this hypothesis using dichotic listening measures of functional asymmetry. Both alcoholics and older nonalcoholics evidenced patterns of cognitive preservation and impairment similar to those seen in patients with known right hemisphere dysfunction. Nevertheless, dichotic listening findings did not reveal any selective effect on the right hemisphere, as previously proposed. The dichotic studies supported the view that both hemispheres are affected by aging and alcoholism. Patients with right hemisphere lesions demonstrated characteristic and predictable changes in dichotic asymmetries, illustrating the reliability of the dichotic measures as indices of hemispheric function.