Table 1.

Characteristics of the participants

	Harvard aging brain study			Alzheimer’s disease neuroimaging initiative
Clinical diagnoses	CN (n = 279)	MCI (n = 51)	AD (n = 16)	CN (n = 367)	MCI (n = 523)	AD (n = 197)
Age, y	73.7 (6.1)	72.8 (8.8)	68.1 (9.7)†	74.7 (6.6)	72.7 (7.9)†	75.3 (7.8)
Education, y	15.8 (3.0)	16.5 (3.1)	15.5 (2.3)	16.5 (2.6)	16.1 (2.7)*	15.9 (2.7)*
Female, %	59.5%	35.3%*	31.3%*	53.1%	43.2%*	41.6%*
E4 carriers, %	29.0%, missing = 3	40.6%,† missing = 19	75.0%,† missing = 12	27.8%, missing = 0	46.7%,† missing = 0	64.5%,† missing = 0
Baseline MMSE	29.0 (1.0)	27.6 (1.4)†	20.1 (4.1)†	29.0 (1.2)	28.0 (1.7)†	22.8 (3.1)†
PET-Aβ stages, 0/1/2; N and %	192/44/40; 70/16/14%	23/6/22†; 45/12/43%	1/0/15†; 6/0/94%	228/110/28; 62/30/8%	209/152/162†; 40/29/31%	24/38/134† 12/19/68%
Serial PET interval, y	3.4 (1.3), missing = 135	2.3 (0.9), missing = 47	3.2 (1.5), missing = 14	2.4 (0.8), missing = 99	2.6 (0.9),* missing = 161	2.2 (0.6), missing = 146
Cognitive follow-up, y	3.6 (1.3)	2.7 (2.2) †	N/A	3.1 (1.4)	3.3 (1.4)*	N/A

Abbreviations: Aβ, amyloid β; AD, Alzheimer’s dementia; CN, clinically normal participants; MCI, mild cognitive impairment.

NOTE. * and ^† represent values significantly different from CN of the corresponding cohort.

^*P < .050

^†P < .001

NOTE. Statistics: two-sample t-tests except for sex, genotype, and PET-Aβ stages for which χ² are used.

NOTE. Age and MMSE are given at the closest time of baseline PET.

NOTE. N/A represents that cognitive follow-up data were not analyzed in participants who had AD dementia at baseline.