Geographical remote memory and verbal fluency in Alzheimer's disease

It has been previously shown that persons with Alzheimer's disease (AD) hav e impaired remote memory for geographical information. In particular, indiv iduals with AD have greater difficulty locating specific (i.e., cities) vis -a-vis gross (i.e., states) geographical features on a map. Similarly, it h as been found that individuals with AD are disproportionately impaired in p roducing specific exemplars relative to category labels on category (semant ic) verbal fluency tasks. One intent of this study was to replicate the fin dings concerning remote spatial memory and to determine whether persons wit h AD also show disproportionate impairment in retrieving specific rather th an more global information on geographical verbal fluency (cities and state s) tasks. A 2nd purpose of the study was to examine the relation between ge ographical spatial memory and geographical verbal fluency tasks and to addr ess whether a similar mechanism might underlie impaired performance on thes e tasks. Our findings indicated that, compared to an age and education matc hed control group, the AD group was disproportionately impaired in locating cities relative to states on the Fargo Map Test-Revised (FMT-R). Similarly , the AD group showed a more pronounced impairment on the city than state v erbal fluency task. The control group's scores on the FMT-R and geographica l fluency tasks were not significantly correlated, whereas those of the AD group were correlated. This suggests that a similar mechanism (a retrieval deficit or bottom-up breakdown of hierarchically organized spatial knowledg e) might underlie the AD group's impairment in geographical knowledge.