Predicting progression from subjective cognitive decline to dementia using different neuropsychological criteria: A longitudinal study

BACKGROUND: Subjective Cognitive Decline (SCD) is considered a risk stage for future cognitive impairment and dementia. OBJECTIVE: This study examined whether different neuropsychological criteria for defining cognitive normality influence SCD's ability to predict conversion to dementia. METHODS: Participants from the Cognitive Complaints Cohort were diagnosed according to the Subjective Cognitive Decline Initiative criteria. Normal cognition was defined by the absence of Mild Cognitive Impairment according to five Jak and Bondi criteria. Sociodemographic, clinical, and neuropsychological data were analyzed using descriptive statistics. Bootstrap methods characterized group profiles given overlap between SCD definitions. Kaplan-Meier curves illustrated time to dementia, and a clustered Cox proportional hazards model accounted for overlapping group membership and adjusted for baseline variables. RESULTS: Among 838 subjects, the five SCD groups showed similar age and sex distributions but differed in education, cognition, and functional status, while subjective complaints and depressive symptoms did not differ meaningfully. Kaplan-Meier curves showed variability in conversion probabilities. At five years, conversion ranged from 3.9% (Liberal) to 25.5% (Conservative); at ten years, from 16.2% to 40.9%. Clustered Cox analysis showed that Conservative and Historical SCD remained associated with higher hazard of conversion after adjustment, whereas Typical and Comprehensive SCD were associated with lower hazard estimates. CONCLUSIONS: Neuropsychological criteria for cognitive normality define SCD groups with distinct clinical profiles and risks of dementia. Broader definitions identify individuals at higher risk, whereas more stringent definitions capture populations with lower likelihood of decline, highlighting the importance of criterion selection according to clinical and research objectives.