Table 3 Demographic, clinical and health variables by subgroup

	NP normal/ CDR normal (n = 1451) Subgroup 1	NP normal/ CDR MCI (n = 751) Subgroup 2	NP MCI/CDR normal (n = 381) Subgroup 3	NP MCI/CDR MCI (n = 480) Subgroup 4	ANOVA F or χ²
Demographic variables
Age	78.0 (2.9)^a	78.7 (3.4)^b	78.7 (3.5)^c	79.6 (3.7)^d	31.62***
Education (years)	14.5 (2.8)^a	13.8 (2.8)^b	15.0 (3.1)^c	14.2 (3.3)^a	19.72***
Gender (% female)	690 (47.6%)^a	317 (42.2%)^b	172 (45.1%)^{a b}	237 (49.4%)^a	χ² = 7.99*
Mental Status Tests
ADAS	5.6 (2.1)^a	6.7 (2.6)^b	7.1 (2.7)^c	8.4 (3.2)^d	159.73***
3MSE	95.0 (3.8)^a	93.1 (4.4)^b	92.2 (4.4)^c	89.7 (5.4)^b	189.28***
Premorbid functioning
AMNART IQ	118.3 (7.8)^a	115.7 (8.1)^b	116.1 (8.7)^b	113.7 (9.2)^c	41.29***
Raven CPM	29.7 (4.1)^a	28.9 (4.0)^b	26.5 (4.9)^c	25.7 (4.9)^d	129.29***
Clinical/health variables
ApoE 4 allele (% carriers)†	237 (20.0%)	133 (22.3%)	64 (21.3%)	88 (24.2%)	χ² = 3.39
CESD depression scale	3.2 (3.1)^a	3.9 (3.7)^b	3.4 (3.4)^a	4.6 (4.1)^c	24.13***
Sum endorsed health problems (out of 24)	1.8 (1.6)^a	2.1 (1.8)^b	1.9 (1.8)^{a b}	2.1 (1.8)^b	7.31***
Difficulty with IADLs (% yes)	383 (26.4%)^a	239 (31.8%)^b	119 (31.3%)^b	177 (36.9%)^b	χ² = 21.29***
No of medications (Rx and OTC)	7.1 (3.9)	7.5 (4.2)	7.0 (3.8)	7.2 (3.9)	0.54
Mobility: difficulty walking half mile‡ (% yes)	277 (19.2%)^a	167 (22.4%)^a	85 (22.7%)^a	143 (30.2%)^b	χ² = 24.09***
Outcome
Deaths	177 (12.2%)	104 (13.8%)	43 (11.3%)	59 (12.3%)	χ² = 1.90
Dropouts	77 (5.3%)^a	47 (6.3%)^{a b}	26 (6.8%)^{a b}	44 (9.2%)^b	χ² = 9.28*
Dementia	107 (7.4%)^a	129 (17.2%)^b	87 (22.8%)^c	199 (41.5%)^d	χ² = 307.40***

Values are mean (SD) or n (%).
Means or proportions within a given row with different superscripts (^{a, b, c, d}) are statistically different by Student–Neuman–Keuls procedure or modified Keppel–Bonferonni correction, respectively. Site included as covariates in omnibus ANOVAs.
*p<0.05, ***p<0.001.
†Reduced sample with ApoE genotyping, total n = 2445 (see methods).
‡Self-report.
3MSE, Modified Mini-Mental State Examination; ADAS, Alzheimer’s Disease Assessment Scale; AMNART, National Adult Reading Test-American version; ApoE, apolipoprotein E; CDR, Clinical Dementia Rating; CESD, Center for Epidemiological Studies Depression Scale; IADL, instrumental activities of daily living; MCI, mild cognitive impairment; NP, neuropsychological; OTC, over the counter; Raven CPM, Raven’s Coloured Progressive Matrices.