Abstract

Aims

To identify optimal Cognitive Composites (CCs) domain scores related to conversion to dementia from Mild Cognitive Impairment (MCI).

Methods

MCI > 44 years old from the Ace Alzheimer Center cohort (n = 2421) were included. Neuropsychological variables were approached under an exploratory and confirmatory factorial analysis (FA). Three relevant clinical MCI phenotypes were considered: early vs. late onset, amnestic vs. non-amnestic, and probable vs. possible. Cox proportional hazard ratio and Kapplan-Meier analysis were calculated to estimate risk of conversion and survival times to dementia, considering the CCs obtained in confirmatory FA and their interaction with the three clinical phenotypes. The model was controlled by age, sex, and education.

Results

Exploratory and confirmatory FAs supported a five-factor CCs domain scores: Processing Speed, attention and working memory (A-WM), verbal fluency, memory and visuospatial-praxis (V-P). Survival analysis showed that worst CCs domain scores main factors, except for A-WM, with a non-significant association, were associated with a higher risk of conversion. Interaction effects showed that V-P was modulated by early-late onset (Wald=10.93, p=.001, HR=.65) and probable vs. possible conditions (Wald= 6.31, p=.012, HR=1.16). The predictive risk conversion of V-P performance was increased among late-onset and probable patients. Early vs. late-onset and probable vs. possible conditions showed a significant interaction effect (HR= 1.93, p=.021). Accumulation of probable and late conditions in a patient emerges as a critical condition of conversion risk.

Conclusions

Among MCI patients followed in a Memory Unit, CCs domain scores emerge as consistent predictors of conversion to dementia, even when considering other relevant phenotypic variables.

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