Table 2.

PET-Aβ stage frequencies after a 3-year PET follow-up

	Follow-up PET
Baseline PET stage	PET stage	HABS	ADNI	Total
PET-Aβ stage 0	PET-Aβ stage 0	N = 91, 85.0%	N = 293, 88.3%	N = 384, 87.5%
Low cortical	PET-Aβ stage 1	N = 14, 13.1%	N = 34, 10.5%	N = 49, 11.1%
Low striatal	PET-Aβ stage 2	N = 1, 0.9%	N = 3, 0.9%	N = 4, 0.9%
HABS, N = 107	Low cortical	N = 1, 0.9%	N = 1, 0.3%	N = 2, 0.5%
ADNI, N = 332	High striatal
PET-Aβ stage 1	PET-Aβ stage 1	N = 12, 57.1%	N = 157, 85.3%	N = 169, 82.4%
High cortical	PET-Aβ stage 2	N = 9, 42.9%	N = 26, 9.2%	N = 26, 12.7%
Low striatal	PET-Aβ stage 0	N = 0, 0.0%	N = 10, 5.4%*	N = 10, 4.9%
HABS, N = 21	Low cortical	N = 0, 0.0%	N = 0, 0.0%	N = 0, 0.0%
ADNI, N = 184	High striatal
PET-Aβ stage 2	PET-Aβ stage 2	N = 22, 100.0%	N = 137, 84.0%	N = 159, 85.9%
High cortical	PET-Aβ stage 1	N = 0, 0.0%	N = 26, 16.0%*	N = 26, 14.1%
High striatal	PET-Aβ stage 0	N = 0, 0.0%	N = 0, 0.0%	N = 0, 0.0%
HABS, N = 22	Low cortical	N = 0, 0.0%	N = 0, 0.0%	N = 0, 0.0%
ADNI, N = 163	High striatal

Abbreviations: Aβ, amyloid β; ADNI, Alzheimer’s Disease Neuroimaging Initiative; HABS, Harvard Aging Brain study.

NOTE. The table shows the number of participants classified in a given PET stage (0, 1, 2) at baseline and at follow-up (total N = 829). Percentages are the proportions of participants in each possible stage at follow-up PET from the total number of participants in a given stage at baseline PET. Results are first split by cohort and then grouped together.

^*Indicate backward transitions, which are only observed in ADNI, not in HABS.