Table 1.

Characteristics of amyloid negative and amyloid positive individuals at baseline

	Amyloid negative (n=183)	Amyloid positive (n=61)	Group difference
			t / χ	P (unadjusted)
Age (years)	73.48 (6.23)	75.62 (6.16)	−2.34	0.021*
Education (years)	15.62 (3.20)	16.34 (2.81)	−1.68	0.097
Sex (Female, n (%))	110 (60.11%)	37 (60.66%)	0.01	0.940
APOE+ (n, %)^	33 (21.29%)	29 (53.70%)	20.64	5.541e-06***
MMSE (score)	29.04 (1.08)	28.85 (1.08)	1.17	0.247
Memory factor score	−0.037 (0.75)	−0.035 (0.73)	−0.02	0.987
PiB - PET levels (DVR)	1.085 (0.05)	1.421 (0.15)	−17.72	2.2e-16***
Left hippocampal volume	3680.64 (451.37)	3533.08 (484.21)	2.10	0.039*
Right hippocampal volume	3791.47 (404.59)	3639.10 (468.65)	2.27	0.025*
Left HCB, FA	0.354 (0.03)	0.353 (0.03)	0.28	0.784
Right HCB, FA	0.348 (0.03)	0.346 (0.04)	0.46	0.648
Left HCB, MD$	0.879 (0.10)	0.887 (0.10)	−0.53	0.598
Right HCB, MD$	0.890 (0.11)	0.911 (0.13)	−1.14	0.256
Left PCC tau (SUVr)#	1.192 (0.16)	1.301 (0.20)	−2.91	0.005**
Right PCC tau (SUVr)#	1.242 (0.16)	1.309 (0.19)	−1.93	0.059

Mean and standard deviations (or n and % for dichotomous variables) are provided. Two-sided Welsh t-tests were used to calculate group differences for the continuous variables and chi-square for comparing proportions across both groups. Hippocampal volumes are adjusted for intracranial volume.

Abbreviations: MMSE = Mini-Mental State Examination, PiB = Pittsburg Compound B, DVR = dynamic volume ratio, HCB = Hippocampal cingulum bundle, FA = Fractional Anisotropy, MD = Mean Diffusivity. CI = Confidence interval;

^*p < 0.05;

^***p < 0.001,

^#tau binding levels are from the first tau PET measurement (103 amyloid negative; 36 amyloid positive individuals),

^{^}Missing data for APOE ε4 status for amyloid negative (n=28) and amyloid positive (n=7) individuals,

^$MD measures were multiplied by 1000. Axial and Radial diffusivity values correlated with the MD measurements at r = 0.96 and r = 0.99 respectively.