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AlzRisk Paper Detail
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Reference: Beydoun, 2008
Cohort: Baltimore Longitudinal Study of Aging
Risk Factor: Obesity


Exposure Detail
The authors evaluated effect estimates for men and women separately between ages 30-35, 35-40, and 40-45. The data given in this row correspond to men of ages 35-40.

Method of ascertaining BMI: technician measurement

"Height and weight were measured with calibrated scales
by trained technicians. At each study visit, BMI was calculated."

"Linear mixed models were fitted to sample 1 (n = 3,005
subjects) to estimate predicted values of BMI and waist circumference at ages 30, 35, 40, 45, and 50 years, using age at visit as the time variable (the method is described in Web Appendix 1, presented on the Journal’s website (http://aje.oxfordjournals.org/)). Predicted BMI values at each target age were categorized on the basis of World Health Organization guidelines (32) as follows: <18.5 (underweight), 18.5–24.9 (normal), 25–29.9 (overweight), and >= 30 (obese)."

"BMI change over a period of 5 years was also calculated and grouped into 3 categories (<10th percentile, 10th-90th percentile and >90th percentile)".

"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."

Age Detail
"Subjects entered follow-up at age 30 years, were entered
into the risk set at age 50 years, and exited follow-up at first failure, defined as being diagnosed with incident AD at or beyond age 50 years or being censored at the end of follow-up due to death or attrition."

Screening and Diagnosis Detail
AD Diagnosis:
NINCDS ADRDA National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association Criteria (McKhann 1984)

"Subjects showing changes that indicated incident dementia
were systematically studied. Diagnoses of dementia and
dementia type were formulated during multidisciplinary
evaluations based on prospectively collected evidence using
National Institute of Neurological and Communicative Disorders and Stroke–Alzheimer’s Disease and Related Disorders Association criteria (31). Estimation of age at AD onset was based on informant reports and history of disease-free examinations."

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

AD Covariates:
Aage
Eeducation
Ggender
RErace/ethnicity
SMsmoking status
YOByear of birth