Diagnostic classification

Cognitive diagnoses were assigned algorithmically (decision tree) and verified at consensus review by an expert in the field of dementia as follows: Cognitively Unimpaired (CU) = no cognitive complaints, CDR sum of boxes score of 0 and cognitive test scores broadly within normal limits (i.e., performance greater than that defined as meeting diagnostic criteria for MCI [i.e.,< = 1.5 standard deviations below the normative range]). Of note, participants with an isolated cognitive test score 1.5 SD below adjusted z-scores, who had no cognitive or functional complaints were assigned as CU; Mild Cognitive Impairment (MCI): cognitive complaints (self or other), CDR sum of boxes score between 0.5-2.0 and at least one cognitive test score falling 1.5 standard deviations below normative ranges; Dementia: CDR sum of boxes score> = 2.5 and at least two cognitive test scores 2 standard deviations below normative ranges. In this study, we examined participants classified in the following groups: cognitively impaired (MCI+AD), and cognitively unimpaired.