Subtle alterations of autobiographical memory and spatiotemporal processing in subjective cognitive decline

The deterioration of autobiographical memory (AM) and autonoetic consciousness is central in Alzheimer's Disease (AD). Here, we investigated the presence of AM alterations in a potential preclinical stage of AD known as Subjective Cognitive Decline (SCD), characterized by a self-reported worsening in cognitive functioning without an objective cognitive impairment. Considering the key role of spatial and temporal components in episodic features of AM, we further hypothesized that alterations in such components may be highlighted in SCD, and investigated possible modifications in these functions with tasks tapping environmental navigation and duration processing. Finally, the level of cognitive complaints was also considered a factor that may modulate performance.

Performance of 31 individuals with SCD was compared with that of 31 healthy control participants matched for age, gender, and education. AM was assessed using the Autobiographical Interview and the Autobiographical Fluency Task (AFT). Environmental navigation was investigated using a battery assessing route, landmark, and survey knowledge, and landmark ordering. Temporal processing was assessed with computerized tasks investigating retrospective and prospective duration processing.

SCD produced more items in the personal semantics condition of the AFT compared with healthy controls, while showing reduced performance in landmark recognition and survey knowledge. When considering cognitive complaints, which are known to play a role in modulating performances in SCD, results showed a positive association between scores on the Cognitive Failure Questionnaire and scores on the semantic condition of the AFT, and a significant negative correlation between scores on the Cognitive Failure Questionnaire and performance in retrospective duration processing.

Findings suggest that subtle alteration of AM and spatiotemporal processing can be identified in SCD, and that the level of cognitive complaints may be a relevant factor in modulating spatiotemporal processing and autobiographical memory in this population.