Retrograde Amnesia for Episodic and Semantic Memories in Amnestic Mild Cognitive Impairment

Abstract

Abstract. Retrograde amnesia (RA), which includes loss of memory for past personal events (autobiographical RA) and for acquired knowledge (semantic RA), has been largely documented in patients with amnestic mild cognitive impairment (aMCI). However, previous studies have produced controversial results particularly concerning the temporal extent of memory impairment. Here we investigated whether, with the onset of hippocampal pathology, age of memory acquisition and retrieval frequency play different roles in modulating the progressive loss of semantic and episodic contents of retrograde memory respectively. For this purpose, aMCI patients and healthy controls were tested for the ability to recall semantic and autobiographical information related to famous public events as a function of both age of acquisition and retrieval frequency. In aMCI patients, we found that the impairment in recollecting past personal incidents was modulated by the combined action of memory age and retrieval frequency, because older and more frequently retrieved episodes are less susceptible to loss than more recent and less frequently retrieved ones. On the other side, we found that the loss of semantic information depended only on memory age, because the remoteness of the trace allows for better preservation of the memory. Our results provide evidence that the loss of the two components of retrograde memory is regulated by different mechanisms. This supports the view that diverse neural mechanisms are involved in episodic and semantic memory trace storage and retrieval, as postulated by the Multiple Trace Theory.

Exploring mechanisms that affect retrograde memory for public events in amnestic mild cognitive impairment: A longitudinal update

“…Period A: 1969–78; Period B: 1997–2001; Period C: 2009–13) was assessed using two different procedures, that is, free recall and recognition tests. In order to potentially control for difference in media exposure, the six famous events were selected from a large set of 50 public events because they were judged as widely‐known and frequently‐retrieved by at least 70% (range 70%–85%) of the experimental sample in a previous study (De Simone, Fadda, et al, 2017). In the free recall procedure, the participants were asked to try to remember as much information as possible about the public events without any cue or suggestion (only specific prompts were allowed in order to elicit as much detail as possible, that is “What happened?” “Where and when did the event take place?” “Who was involved?”).…”

“…Retrograde memory impairments have been widely documented in patients with amnestic mild cognitive impairment (a‐MCI) and Alzheimer's disease (AD) from the earliest stages of the disease (De Simone et al, 2016; De Simone, Fadda, et al, 2017; Leyhe et al, 2009; Serra et al, 2020, 2022). However, the nature of this memory impairment in relation to the underpinning cognitive processes responsible for the failure to remember remote information has not yet been extensively explored.…”

Episodic and Semantic Autobiographical Memory in Mild Cognitive Impairment (MCI): A Systematic Review

“…The situation is more controversial for what concerns the semantic component. Fourteen studies out of twenty-one have studied this aspect, while seven articles [26,32,[34][35][36][37][38] focused only on the episodic component. Among the 14 articles that analyzed autobiographical semantic memory, 4 of them [21,24,29,33] have not found any significant differences in semantic memory scores between patients with MCI and healthy controls.…”

“…In our review, 13 studies [16,[21][22][23][24][25][26]28,31,34,35,37,39] examined the temporal gradient in the recall of episodic autobiographical memories in patients with MCI. Three articles [21][22][23] did not find significant differences in time-period performance.…”

Memory for public events in amnestic mild cognitive impairment: The role of hippocampus and ventro‐medial prefrontal cortex

“…More recently, a study assessing the famous people knowledge in AD and aMCI patients found evidence of temporal gradient for enduring famous people but not for transient famous people (Benoit et al, 2017). De Simone et al, (2017) investigated a group of aMCI patients and found evidence for a strong temporal gradient in the recall of public events as well as of personal incidents that were related to the occurrence of public events. In a second study, which aimed at assessing the contribution of storage and retrieval processes on the pattern of retrograde memory impairment, the same group reported the presence of temporal gradient in the recall performance of both aMCI and AD patients (De Simone et al, 2020).…”