Subjective cognitive concerns, amyloid-b, and neurodegeneration in clinically normal elderly

Abstract

Objective: To determine whether neuroimaging biomarkers of amyloid-b (Ab) and neurodegeneration (ND) are associated with greater self-reported subjective cognitive concerns (SCC) in clinically normal older individuals. Methods: A total of 257 participants underwent Pittsburgh compound B PET, PET with fluorodeoxyglucose 18F, and structural MRI, as well as a battery of neuropsychological measures including several questionnaires regarding SCC. Individuals were classified into 4 biomarker groups: biomarker negative (Ab2/ND2), amyloidosis alone (Ab1/ND2), amyloidosis plus ND (Ab1/ND1), and ND alone (Ab2/ND1). Results: Both Ab and ND were independently associated with greater SCC controlling for objective memory performance. By contrast, neither Ab nor ND was associated with objective memory performance controlling for SCC. Further examination revealed greater SCC in individuals with Ab or ND positivity compared to biomarker-negative individuals. In addition, greater SCC predicted Ab positivity when controlling for ND status. Conclusions: When individuals were grouped by biomarker status, those who were positive on Ab or ND had the highest report of SCC compared to biomarker-negative individuals. Findings were consistent when SCC was used to predict Ab positivity. Taken together, results suggest that both Ab and ND are associated with SCC, independent of objective memory performance. Enrichment of individuals with SCC may increase likelihood of Ab and ND markers in potential participants for secondary prevention trials.