[Hemisphere differences in aging: an artifact]

The observation that language processes in particular resist aging relatively well, gave rise to the hypothesis that the right hemisphere declines more rapidly than the left. In this review we discuss results from different lines of research relevant to this issue. It appears that the hypothesis is based on methodologically weak studies. Factors such as task characteristics, familiarity with stimulus materials and practice effects have been controlled insufficiently in the past and they may well explain the observed effects. Moreover, no clear neuropathological differences between the hemispheres have been reported. Therefore, it seems reasonable not to assume differential rates of aging for the two hemispheres.