Moderating effect of the domains of the cognitive reserve index questionnaire (CRIq) on longitudinal change slopes in episodic memory across the cognitive aging continuum.

Cognitive reserve (CR) hypothesis predicts reduced impact of aging and neurodegeneration on cognition in adults who have lived in cognitively stimulating environments. Our study tested the moderating role of socio-behavioral CR proxies on longitudinal episodic memory (EM) decline, one of the cognitive domains that has been suggested to be most sensitive to early deterioration in presymptomatic stages of dementia. 323 participants (≥ 50 years old) from CompAS study were classified into four groups based on baseline diagnosis and progression at 18-24 (T1) and 48-70 months (T2): Subjective cognitive complaints (SCC) who remain stable (SCC-stable), Mild cognitive impairment (MCI) who remain stable (MCI-stable), SCC who progressed to MCI (Prog-to-MCI), and SCC or MCI who progressed to dementia (Prog-to-Dem). Mixed models analyzed changes across EM measures of immediate and long delay with and without cued recall from the Spanish CVLT to account for the EM processes of encoding and consolidation in the short and long term. Domains from Cognitive Reserve Index Questionnaire (School, Work and Leisure) were tested as moderators of longitudinal EM trends in progression groups across two nested models. Our results confirm the CR hypothesis:1) steeper memory decline observed in all progression groups compared to SCC-stable, especially at T2 relative to baseline; 2) Higher CRIq-School and CRIq-Work scores moderated changes in EM measures in participants who progress to MCI and who progress to dementia compared to SCC-stable group; 3) CR moderation effect was stronger at T2. Our findings support the validity of CR proxies of Education and Occupation in attenuating memory decline along the continuum of subjective and objective cognitive decline.