Subjective cognitive impairment and biomarkers of Alzheimer’s disease

Abstract

AbstractBackgroundSubjective cognitive impairment (SCI) is common in older adults. It may represent the earliest clinical manifestation of cognitive decline and Alzheimer’s disease (AD).Objectives1) to evaluate associations between SCI and cerebrospinal fluid (CSF) biomarkers of AD; 2) to identify specific single questions or question combinations that are related to the presence of cerebral AD pathology; 3) to evaluate whether using SCI related scores or specific questions combined with other clinical features and biomarkers may improve prediction of cognitive decline.MethodWe conducted a longitudinal study in 164 non‐demented subjects participating on a biomarker study in a memory clinic setting, aged 53 to 88 years, with CDR scores of 0 (N = 84) and 0.5 (N = 80). SCI was assessed using the Cognitive Complaint Interview (CCI, Thomas‐Antérion et al., 2006), a validated 10 items questionnaire. Accordingly, SCI is defined as present when the subject answers “yes” to 3 or more items; and/or to item 5, and/or to items A, 4, 5, 7, 8. All participants underwent comprehensive neuropsychological evaluations and CSF biomarkers analysis. “Amyloid positivity" and “AD pathology” were defined according to the CSF Aβ1‐42 levels and pTau181/Aβ1‐42 ratio, respectively. Logistic regressions were used to address the associations of interest.ResultsParticipants with SCI had significantly lower Aβ1‐42 and higher Tau and pTau181 levels compared to those without SCI. SCI was associated with amyloid positivity while CCI total score and the question A (reporting changes in memory) were associated with both amyloid positivity and AD pathology in the whole cohort. When performing analysis separately in the CDR = 0 and CDR = 0.5 subgroups the associations remained significant in the CDR = 0.5 group. Only question 6 (difficulties in finding words) was associated with AD pathology in the CDR = 0 group. Results on the prediction of cognitive decline at follow‐up visits will be presented at the conference.ConclusionIn dementia‐free subjects from this memory clinic cohort SCI‐related scores and single questions indicate amyloid positivity and the presence of AD pathology depending on the absence/presence of mild cognitive impairment. Further studies are needed to evaluate the diagnostic and prognostic utility of cognitive complains in memory clinic patients.