Distinct Cognitive and Brain Morphological Features in Healthy Subjects Unaware of Informant-Reported Cognitive Decline

Background: Subtle cognitive decline preceding cognitive impairment can be self-perceived, referred to as subjective cognitive decline (SCD), or go unrecognized. Objective: To study the clinical, cognitive, and structural neuroimaging characteristics of psychometrically normal subjects without self-awareness of cognitive decline (unaware decliners, UD) and to compare them with SCD participants and controls. Methods: 2,640 participants from the ALFA cohort, 1,899 controls, 173 UD (decline reported by the informant only), and 568 SCD underwent clinical and cognitive explorations. A subset of 530 underwent structural MRI (379 Controls; 43 UD; 108 SCD). Linear models adjusting for confounders (age, sex, education, and mood state) were used to assess group differences on cognition and voxel-wise grey matter (GM) volumes. Results: 6.6% were UD while 21.5% SCD. No differences in anxiety and depression were observed between controls and UD, while SCD did (p