Cognitively healthy participant demographic and baseline data.

N is the number of participants; values with parentheses are mean (standard deviations). CDR-SB: Clinical Dementia Rating, sum of boxes score; ADAS-Cog: cognitive subscale of the Alzheimer’s Disease Assessment Scale; MMSE: Mini Mental State Exam. Aβ and ptau: cerebrospinal fluid (CSF) densities of these proteins (see also Table 3); HC: cognitively healthy; Aβ+ means ≤192 pg/ml; ptau+ means ≥23 pg/ml.*Excluding two who had converted to MCI at 24-months.