Script representation in patients with Alzheimer's disease

Abstract

We examined script representation in 26 patients with Alzheimer's disease (AD) compared to 31 healthy elderly subjects (HE). Participants were asked to sort cards describing actions belonging to eight scripts according to the script to which they belonged and according to their order of execution. Each script included actions which were low in centrality and distinctiveness (non-central actions and non-distinctive actions--NCA & NDA), and which were high in centrality (central actions--CA), distinctiveness (distinctive actions--DA), centrality and distinctiveness (central actions and distinctive action--CA & DA). These actions were presented in three conditions. In the first condition (scripts with headers--SH), the 43 actions belonging to three different scripts were given with each script header written on separate cards. The second condition (scripts without headers--SwH) used 46 actions belonging to three other scripts, but no script header was provided. In the third condition (scripts with distractor header--SDH), the 28 actions belonging to two other scripts were given with each script header and a distractor header written on separate cards. The results showed that performance of subjects with AD was significantly lower in all conditions. Overall, AD patients made significantly more sequencing errors than HE subjects. AD patients also committed significantly more sorting errors than HE subjects for all types of actions (NCA & NDA, CA, DA, CA & DA). These data are consistent with the view that AD produces impairment of both the syntactic and semantic dimensions of script representation.