Table 1.

Baseline Characteristics (First Visit) of Subjects According to Number of Follow-Up Visits and Incident Alzheimer's Disease Status, Baltimore Longitudinal Study of Aging, 1958–2006

	All Study Subjects			Subjects at Risk of Alzheimer's Disease
	≥1 Visit (n = 3,005)	1 Visit Only (n = 309)	≥2 Visits (n = 2,696)	No Alzheimer's Disease (n = 2,135)	Alzheimer's Disease (n = 187)
Gender, % women	39.9	53.7	38.3***	36.4	38.0 (NS)
Race/ethnicity, %
Non-Hispanic white	80.7	64.2	82.1***	82.0	96.8***
Non-Hispanic black	16.2	29.7	14.5	15.2	3.2
Other	3.1	6.1	3.8	2.8	0.0
Mean education, years	16.6 (2.8)a	15.7 (3.0)	16.7 (2.7)***	16.6 (2.9)	16.8 (2.7) (NS)
Smoking status, %
Never smoker	38.8	42.5	38.5 (NS)	36.4	39.2***
Former smoker	38.0	34.6	38.2	40.5	48.4
Current smoker	23.2	22.9	23.3	23.1	12.4
Type 2 diabetes mellitus, %	2.5	2.9	2.4 (NS)	3.2	2.1 (NS)
Hypertension, %	32.7	26.8	33.4*	38.3	41.4 (NS)
Cardiovascular disease, %b	5.5	4.5	5.7 (NS)	6.6	13.4***
Dyslipidemia, %	7.3	7.1	7.4 (NS)	7.9	4.3†
Mean age at first visit, years	52.1 (17.7)	46.9 (18.5)	52.8 (17.2)***	56.9 (15.4)	68.6 (12.1)***
≤20	0.4	0.6	0.4***	0.0	0.0***
21–29	13.5	21.0	12.6	4.6	0.0
30–39	15.3	24.3	14.3	11.8	0.5
40–49	18.3	15.2	18.5	18.1	10.2
50–59	16.3	13.3	16.6	21.1	15.0
60–69	15.9	9.1	16.7	20.6	20.3
70–79	14.4	11.0	14.9	17.0	36.4
≥80	5.9	5.5	6.0	6.9	17.6
Mean body mass indexc	25.2 (3.9)	25.4 (4.8)	25.2 (3.8) (NS)	25.4 (3.8)	24.7 (3.3)**
Underweight (BMI ≤18.5)	1.6	3.0	1.4*	1.1	2.7*
Normal weight (BMI 18.6–24.9)	52.2	50.3	52.4	49.3	56.1
Overweight (BMI 25.0–29.9)	35.7	33.4	36.0	38.4	35.3
Obese (BMI ≥30)	10.6	13.2	10.1	11.1	5.9

Abbreviation: NS, not significant.

^†P ≤ 0.10 (borderline-significant); *P < 0.05; **P < 0.01; ***P < 0.001; NS: P > 0.10.

^aNumbers in parentheses, standard deviation.

^bReporting any of the following conditions at the baseline visit: stroke, congestive heart failure, nonfatal myocardial infarction, or atrial fibrillation.

^cWeight (kg)/height (m)².