Table 1.

Average characteristics by biomarker group Abbreviations: A±: amyloid positive or negative; HA±: hippocampal degeneration positive or negative. See text for definitions of cutoffs. CDR: CDR sum of boxes scores, at baseline and follow up times. Similarly for MMSE. PiB –Baseline: average time interval between PiB imaging and baseline scan (positive means PiB acquisition was later).

Biomarker Category	N	Interscan Interval (Years)	PiB – Baseline (Years)	CDR1	CDR2	MMSE1	MMSE2
A-HA-	18	3.82	3.09	0.56	0.42	28.3	28.1
A+HA-	12	4.07	3.08	0.50	0.71	28.7	28.2
A-HA+	12	3.76	2.04	0.29	0.75	29.0	28.0
A+HA+	11	3.49	2.50	0.73	1.68	28.4	26.9
All Normals	53	3.80	2.73	0.52	0.82	28.6	27.9