‘Language of the past’ – Exploring past tense disruption during autobiographical narration in neurodegenerative disorders

Abstract

Compromised retrieval of autobiographical memory (ABM) is well established in neurodegenerative disorders. The recounting of autobiographical events is inextricably linked to linguistic knowledge, yet no study to date has investigated whether tense use during autobiographical narration is disrupted in dementia syndromes. This study investigated the incidence of correct past tense use during ABM narration in patients with Alzheimer's disease (AD, n = 10) and semantic dementia (SD, n = 10) in comparison with healthy older Controls (n = 10). Autobiographical narratives were analysed for episodic content (internal/external) and classified according to tense use (past/present). Across both patient groups, use of the past tense was significantly compromised relative to Controls, with increased levels of off-target present tense verbs observed. Voxel-based morphometry analyses based on structural MRI revealed differential associations between past tense use and regions of grey matter intensity in the brain. Bilateral temporal cortices were implicated in the SD group, whereas frontal, lateral, and medial temporal regions including the right hippocampus emerged in AD. This preliminary study provides the first demonstration of the disruption of specific linguistic constructs during autobiographical narration in AD and SD. Future studies are warranted to clarify at what point in the disease trajectory such deficits in tense use emerge, and whether these deficits are a product or contributing factor in memory disruption in these syndromes.

External details revisited – A new taxonomy for coding ‘non‐episodic’ content during autobiographical memory retrieval

“…The proposal that external details for recent ABMs in SD are more likely to be influenced by episodic, rather than general semantic, processes is further supported by our finding of robust negative correlations between recent EE and measures of semantic memory in this group (all r values stronger than −.6). This fits well with the well‐established sparing of episodic memory processes in SD, at least in the early stages of the disease trajectory (see Supporting Information; and Adlam, Patterson, & Hodges, ; Irish, Hornberger, et al ., ; Irish et al ., ; Matuszewski et al ., ). Narratives of recent ABMs in AD patients, by contrast, contained elevated amounts of EE, most likely attributable to AD patients’ reliance on semantic facets of retrieved events.…”

Connected Language in Late Middle-Aged Adults at Risk for Alzheimer’s Disease

“…For evaluation that more closely approximates language demands of everyday life, researchers have turned to assessment of spontaneous, connected speech, both as a diagnostic resource as well as a research tool toward understanding the subtle deficits reported by patients in their natural settings. Connected language is elicited by having an individual produce spoken or written language in response to a particular question or stimulus, including picture description tasks[18-21], familiar story re-telling [22] (e.g., “Cinderella” story) , wordless picture book descriptions [23], and general autobiographical interviews [24]. Language is then analyzed using measures such as efficiency (e.g., idea density), conciseness (e.g., how many words required to express an idea), complexity (e.g.…”

Language in Amnestic Mild Cognitive Impairment and Dementia of Alzheimer’s Type: Quantitatively or Qualitatively Different?

“…Although personal semantic knowledge appears to remain intact in MCI, autobiographical recollection of the episodic details associated with a happening experienced during a specific time and place are reduced when compared to same-aged controls [39]. Preserved language skills are critical for communicating autobiographical information, and a recent study investigating language and autobiographical memory in individuals with DAT and semantic dementia found that both groups produced an increased level of off-target present tense verbs where past tense verbs should be expected, begging an answer to the question of whether these deficits are a product or contributing factor in memory impairment [40]. Future research should examine these features in autobiographical recollection in MCI.…”