Non-associative lexical priming is impaired in Alzheimer's disease.

A word-fragment completion task was used to assess long-term, non-associative lexical priming in patients with probable Alzheimer's disease (AD) and age- and education-matched elderly normal control (NC) subjects. Despite equivalent baseline performance, the AD patients exhibited less facilitation in their ability to complete word fragments from having previously read the intact words than did the NC subjects. The AD patients were also impaired relative to NC subjects on an explicit recognition memory task, but there was no relationship between explicit memory performance and priming for either group. These results are consistent with previous demonstrations of impaired semantically-based priming in patients with AD and extend the domain of their impairment to priming that is predominantly based on lexical activation.