Subjective cognitive decline and risk of MCI

Abstract

<h3>Objective</h3> We investigated different dimensions of subjective cognitive decline (SCD) to determine which was the best prognostic risk factor for incident mild cognitive impairment (MCI) among cognitively unimpaired participants. <h3>Methods</h3> We included 1,167 cognitively unimpaired participants, aged 70 to 95 years, from the Mayo Clinic Study of Aging based on 2 concurrent SCD scales (part of the Blessed memory test and the 39-item Everyday Cognition [ECog] scale, which included a validated 12-item derivative) and a single question assessing worry about cognitive decline. We evaluated multiple ways to dichotomize scores. In continuous models, we compared average scores on 4 ECog domains and multidomain (39- and 12-item) ECog scores. Cox proportional hazards models were used to assess the association between each measure and risk of MCI in models adjusted for objective memory performance, depression, anxiety, sex, <i>APOE</i> ε4 carriership, and medical comorbidities. <h3>Results</h3> It was possible to select a substantial group of participants (14%) at increased risk of incident MCI based on combined baseline endorsement of any consistent SCD on the ECog (any item scored ≥3; 12-item ECog hazard ratio [HR] 2.17 [95% confidence interval 1.51–3.13]) and worry (HR 1.79 [1.24–2.58]) in an adjusted model combining these dimensions. In continuous models, all ECog domains and the multidomain scores were associated with risk of MCI with a small advantage for multidomain SCD (12-item ECog HR 2.13 [1.36–3.35] per point increase in average score). Information provided by the informant performed comparable to self-perceived SCD. <h3>Conclusion</h3> Prognostic value of SCD for incident MCI improves when both consistency of SCD and associated worry are evaluated.