Updating deficits in subjective cognitive decline: A differential pattern of executive dysfunction across clinical...

Identifying objective cognitive markers in the preclinical stage of Alzheimer's disease (AD), particularly in Subjective Cognitive Decline (SCD), is critical for early intervention. While executive function comprises three core components (inhibition, updating/switching), their impairment trajectory during the SCD-to-Mild Cognitive Impairment (MCI) progression remains unclear. This study aims to systematically compare these components among Cognitively Normal (NC), SCD, and MCI individuals to determine the earliest sensitive cognitive indicators of AD pathology. Community-dwelling adults aged ≥50 years were classified into NC, SCD, and MCI groups based on comprehensive screening (MoCA, SCD-Q, CDR, ADL). All participants completed standardized computerized tasks assessing inhibition (Oddball, Stop Signal Task), updating (spatial 1-back, VWM task), and switching (task-cue paradigm). One-way ANOVA with post-hoc tests compared group differences in accuracy and reaction time. SCD showed no difference from NC in inhibition but intermediate switch costs; crucially, SCD's spatial 1-back performance was significantly worse than NC and comparable to MCI, indicating early MCI-level updating deficits. Visuospatial storage capacity showed gradual impairment. Updating ability (visuospatial working memory) is the earliest and stably impaired indicator in SCD, serving as a sensitive marker for ultra-early AD screening. These findings suggest that updating ability, particularly visuospatial working memory, is the earliest and most stable impaired executive component, making it a sensitive behavioral marker for identifying high-risk SCD and enabling ultra-early AD screening. In contrast, significant impairments in inhibition and switching are delayed or progressive. This provides new scientific evidence for early assessment and targeted cognitive intervention.