Number-Stroop performance in normal aging and Alzheimer's-type dementia.

The number-Stroop paradigm was used to investigate changes in the inhibitory system and in numerical processing in healthy elderly and individuals with dementia of Alzheimer's type (DAT). The size-congruity effect (i.e., relative to neutral trials, incongruent pairs interfere and/or congruent pairs facilitate either numerical or physical comparison) was found in all groups, though the pattern of interference and facilitation varied across them. Overall, the selective attention breakdown was reflected by the increase in interference shown by the older group and the DAT group. On the other hand, the observation of a standard laterality effect andof automatic numerical processing in all groups suggests that access and retrieval of numerical information is relatively resistant to cognitive deterioration.