Some studies of negative priming and other tasks assumed to reflect
inhibitory functions suggest a decline in inhibitory processes in
Alzheimer's disease. However, none of the measures used in previous
studies can be interpreted as an unambiguous reflection of distractor
inhibition. The present study investigates whether reductions in negative
priming associated with Alzheimer's disease reflect reduced
distractor inhibition, rather than perceptual review processes.
Individuals with early Alzheimer's disease were predicted to show
reduced negative priming on a spatial localization task designed to
provide an unambiguous measure of distractor inhibition. Sixteen clinical
participants showed significantly less negative priming than old and young
healthy control groups, which is interpreted as evidence for reduced
distractor inhibition in early dementia. A second analysis indicated that,
within the clinical sample only, negative priming effect size was
significantly correlated with prime trial response speed. Clinical
participants showing the least negative priming were slower to respond to
an initial stimulus. The results may mean that people with early
Alzheimer's disease have a reduced capacity to use excitatory as well
as inhibitory processes in selection. (JINS, 2006, 12,
416–423.)