Skip to main content
. 2008 Oct 3;168(10):1179–1189. doi: 10.1093/aje/kwn229

Table 2.

Risk of Incident Alzheimer's Disease According to Body Mass Index Status and Change in Body Mass Index at Different Ages (Cox Proportional Hazards Models), Baltimore Longitudinal Study of Aging, 1958–2006a

Range of Values, %b BMIc
Men Range of Values, %b Women
HR 95% CI P Value HR 95% CI P Value
BMI statusd
    At age 30 years
        Underweight 6.05*** 2.14, 17.09 0.001 0.67 0.23, 1.89 0.447
        Normal 1 1
        Overweight 1.17 0.78, 1.75 0.438 1.17 0.59, 2.33 0.657
        Obese 0.70 0.25, 1.96 0.499 2.44† 0.85, 7.00 0.098
    At age 35 years
        Underweight 4.16† 0.99, 17.49 0.052 0.76 0.23, 2.50 0.656
        Normal 1 1
        Overweight 1.05 0.71, 1.55 0.818 1.04 0.51, 2.13 0.910
        Obese 0.57 0.18, 1.87 0.357 2.33 0.81, 6.68 0.116
    At age 40 years
        Underweight 11.89*** 2.82, 50.15 0.001 1.34 0.41, 4.41 0.624
        Normal 1 1
        Overweight 1.07 0.72, 1.58 0.734 1.03 0.52, 2.05 0.928
        Obese 0.41 0.10, 1.58 0.225 2.55† 0.88, 7.37 0.083
    At age 45 years
        Underweight 11.21*** 2.65, 47.30 0.001 1.86 0.57, 6.12 0.303
        Normal 1 1
        Overweight 0.93 0.63, 1.36 0.701 1.24 0.66, 2.32 0.494
        Obese 0.46 0.11, 1.93 0.290 2.66† 0.91, 7.72 0.073
    At age 50 years
        Underweight 2.96 0.68, 12.80 0.147
        Normal 1 1
        Overweight 0.94 0.64, 1.38 0.753 1.11 0.61, 2.04 0.729
        Obese 0.52 0.13, 2.17 0.374 2.43 0.84, 7.02 0.100
Change in BMId
    Between ages 30 and 35 years
        <10th percentile −3.84 to −0.55 1.14 0.70, 1.85 0.592 −5.44 to −0.55 1.91† 0.99, 3.65 0.052
        10th–90th percentile −0.54 to 5.33 1 −0.54 to 5.33 1
        >90th percentile 5.37 to 27.34 4.58** 1.75, 11.95 0.002 5.34 to 19.56 1.16 0.40, 3.37 0.784
    Between ages 35 and 40 years
        <10th percentile −4.01 to −0.64 1.17 0.73, 1.86 0.519 −5.74 to −0.64 1.93* 1.01, 3.72 0.047
        10th–90th percentile −0.62 to 4.88 1 0.62 to 4.88 1
        >90th percentile 5.91 to 21.64 3.82** 1.47, 9.93 0.006 4.92 to 16.40 1.32 0.50, 3.50 0.573
    Between ages 40 and 45 years
        <10th percentile −4.21 to −0.73 1.03 0.64, 1.68 0.891 −6.07 to −0.76 2.00* 1.05, 3.83 0.036
        10th–90th percentile −0.73 to 5.11 1 −0.71 to 5.11 1
        >90th percentile 5.12 to 17.93 5.04** 1.76, 14.42 0.003 5.12 to 14.13 1.35 0.46, 3.91 0.582
    Between ages 45 and 50 years
        <10th percentile −4.47 to −0.78 1.15 0.72, 1.83 0.548 −6.45 to −0.78 1.67 0.87, 3.20 0.121
        10th–90th percentile −0.77 to 4.71 1 −0.77 to 4.71 1
        >90th percentile 4.72 to 15.32 4.68** 1.64, 13.37 0.004 4.72 to 12.41 1.24 0.43, 3.59 0.692

Abbreviations: BMI, body mass index; CI, confidence interval; HR, hazard ratio.

†

P ≤ 0.10 (borderline-significant); *P < 0.05; **P < 0.01; ***P < 0.001.

a

z scores were computed for change, and significant decrease and increase corresponded to the 10th and 90th percentiles (based on the whole Baltimore Longitudinal Study of Aging sample (n = 3,005)), respectively, of the standardized distribution of change. Numbers of subjects and failures were 1,343 and 110, respectively, for men and 671 and 64, respectively, for models with women only.

b

Cutpoints may vary or overlap because of rounding.

c

Weight (kg)/height (m)2.

d

BMI status was categorized as underweight (BMI <18.5), normal (BMI 18.5–24.9), overweight (BMI 25.0–29.9), or obese (BMI ≥30). BMI change was estimated by taking the difference between empirical Bayes predicted values for BMI at each age (using model E in Web Appendix 2) and then computing percent change from baseline. Models with BMI status and change as exposures controlled for education (years), ethnicity (Non-Hispanic black vs. other), and smoking status (former or current smoker vs. nonsmoker).