Overdependence on degraded gist memory in Alzheimer's disease.

TLDR

Alzheimer’s disease reduces associative effects on false recognition in the Deese‑Roediger‑McDermott task, likely due to impaired memory for gist or impaired use of gist in memory decisions. The study aims to determine whether overdependence on degraded gist memory in AD arises from greater impairments in item‑specific recollection. The authors manipulated gist processes by blocking or mixing studied words and varying associative strength, and propose that overdependence on degraded gist memory in AD is caused by larger impairments in item‑specific recollection. Both associative blocking and associative strength had smaller effects on false recognition in AD patients than controls, and blocking affected true and false recognition equally, indicating overdependence on gist; additionally, AD patients showed reduced item‑specific recollection, as true recognition of studied words was lower even when false recognition was matched.

Abstract

Alzheimer's disease (AD) reduces associative effects on false recognition in the Deese-Roediger-McDermott task, either due to impaired memory for gist or impaired use of gist in memory decisions. Gist processes were manipulated by blocking or mixing studied words according to their associations and by varying the associative strength between studied and nonstudied words at test. Both associative blocking and associative strength had smaller effects on false recognition in AD patients than in control participants, consistent with gist memory impairments. However, unlike the case with control participants, blocking influenced true and false recognition equally in AD patients, demonstrating an overdependence on gist when making memory decisions. AD also impaired item-specific recollections, relative to control participants, as true recognition of studied words was reduced even when the two groups were equated on gist-based false recognition. We propose that the overdependence on degraded gist memory in AD is caused by even larger impairments in item-specific recollections.