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Abstract:
Although memory distortion in Alzheimer's Disease (AD) is a
major clinical problem that often contributes to the loss of
independence, the cause of such distortion remains largely
unexplored. We examined false recognition of semantic associates in
patients with AD, age and sex matched elderly adults, and young
adults using a modification of the Deese/Roediger-McDermott
paradigm that provided both a measure of false recognition after a
single exposure to lists of semantic associates, and how false
recognition changed with five presentations of the study list.
Using corrected false recognition scores to control for unrelated
false alarms, we found that (1) false recognition of semantic
associates after a single list exposure was significantly lower in
AD patients than in young and elderly controls; (2) across five
trials corrected false recognition increased significantly in AD
patients and decreased significantly in both young and elderly
adults, resulting in a crossover interaction; (3) all groups showed
an increase in true recognition over the five trials. The pattern
observed in the AD patients is similar to that previously reported
with Korsakoff amnesics, but differs from that reported in
non-Korsakoff amnesics. Signal detection analyses suggest that AD
patients built up semantic gist across trials, whereas both control
groups were able to use increased veridical recollection to
suppress gist-based false alarms.
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