Assessment of associative relations in Alzheimer's disease: Evidence for preservation of semantic memory

Semantic priming was assessed in Alzheimer's disease (AD), elderly control, and young control subjects with three lexical decision, continuous priming experiments. The stimuli were intracategory, associated pairs in Experiments 1 and 2 and varied types of associated pairs in Experiment 3. AD priming effects were equal to those of elderly control subjects; elderly and young control priming effects were also equal. We interpret this as evidence for the relative preservation of the semantic memory network in early AD, as in normal aging, at least to the extent necessary for normal access of concept nodes and normal automatic spreading activation between concept nodes. In a final study (Experiment 4) knowledge of the associations between the targets and related primes used in Experiments 1 and 2 was explicitly assessed; 20 out of 22 AD subjects showed perfect or close to perfect performance.