Memory suppression in Alzheimer’s disease

Abstract

An important challenge for memory is the competition between appropriate and inappropriate information during retrieval. This competition is normally reduced thanks to controlled inhibitory processes that suppress irrelevant memories. In Alzheimer's disease (AD), compromise of suppression ability may result in strong competition between relevant and irrelevant memories during retrieval. The present review highlights this issue by examining studies using the directed forgetting method in AD. This method in which participants are typically instructed to forget no longer relevant information is argued to reflect suppression in memory. Studies using the directed forgetting method suggest that AD participants experience difficulties when they are asked to suppress no longer relevant information in working, autobiographical, source and destination memory. Difficulties in suppressing irrelevant information, as may be observed in AD, may hamper memory retrieval by activating irrelevant memories at the expense of relevant ones.

Off‐track thoughts: Intentional and unintentional mind wandering in Alzheimer's disease

“…One executive function to be evaluated is inhibition (with Stroop tasks). According to the inhibition theory, decline in cognitive performance in aging might reflect an inability to maintain task goals, thereby influencing working memory capacity and attentional control (for a similar view on AD, see Haj). Therefore, deficits of inhibition might lead to processing of task‐irrelevant thoughts rather than of the ingoing activity; this assumption leads to the prediction that inhibitory compromise in normal aging and AD might be associated with mind wandering.…”

Clinical and neurocognitive aspects of hallucinations in Alzheimer’s disease

“…This competition is normally reduced thanks to inhibitory control processes that suppress distractive memories, intrusive or unwanted thoughts, or interfering mental images [62]. Hence, hallucinations in AD patients could be partly due to difficulties in suppressing memory representations, so that unwanted or repetitive thoughts intrude into consciousness.…”

Negative Prospective Memory in Alzheimer’s Disease: “Do Not Perform That Action”

“…Interestingly, inhibitory performance was lower in older adults who made commissions than in those who did not. The implication of inhibitory performance in prospective memory, as observed by Scullin, et al [29], is relevant to our study because AD has been widely associated with inhibitory deficits (for reviews see [30, 31]. These deficits have been observed in studies using the directed forgetting task in which participants are typically instructed to remember or forget certain types of information for a later memory test [32].…”