title: Dementia and dependence: do modifiable risk factors delay disability?
abstract: OBJECTIVE
  To identify modifying factors that preserve functional independence among individuals at high dementia risk.
  
  
  METHODS
  Health and Retirement Study participants aged 65 years or older without baseline activities of daily living (ADL) limitations (n = 4,922) were interviewed biennially for up to 12 years. Dementia probability, estimated from direct and proxy cognitive assessments, was categorized as low (i.e., normal cognitive function), mild, moderate, or high risk (i.e., very impaired) and used to predict incident ADL limitations (censoring after limitation onset). We assessed multiplicative and additive interactions of dementia category with modifiers (previously self-reported physical activity, smoking, alcohol consumption, depression, and income) in predicting incident limitations.
  
  
  RESULTS
  Smoking, not drinking, and income predicted incident ADL limitations and had larger absolute effects on ADL onset among individuals with high dementia probability than among cognitively normal individuals. Smoking increased the 2-year risk of ADL limitations onset from 9.9% to 14.9% among the lowest dementia probability category and from 32.6% to 42.7% among the highest dementia probability category. Not drinking increased the 2-year risk of ADL limitations onset by 2.1 percentage points among the lowest dementia probability category and 13.2 percentage points among the highest dementia probability category. Low income increased the 2-year risk of ADL limitations onset by 0.4% among the lowest dementia probability category and 12.9% among the highest dementia probability category.
  
  
  CONCLUSIONS
  Smoking, not drinking, and low income predict incident dependence even in the context of cognitive impairment. Regardless of cognitive status, reducing these risk factors may improve functional outcomes and delay institutionalization.
authors.affiliation: From the Division of Preventive Medicine (P.M.R.), Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston; Departments of Social and Behavioral Sciences (P.M.R., J.R.M., M.M.G.) and Epidemiology (P.M.R.), Harvard School of Public Health, Boston, MA; Carolina Population Center (B.D.C.), University of North Carolina-Chapel Hill; Institute of Social Science Survey (Q.W.), Peking University, Beijing, China; and the Department of Epidemiology & Biostatistics (M.M.G.), University of California, San Francisco.
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Rist
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Capistrant
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wu
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Marden
authors.forename: M Maria
authors.initials: MM
authors.lastname: Glymour
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000453:epidemiology / Q000209:etiology; D003704:Dementia / Q000453:epidemiology* / Q000523:psychology*; D006233:Persons with Disabilities / Q000523:psychology / Q000706:statistics & numerical data*; D005260:Female; D015577:Geriatric Assessment; D006306:Health Surveys; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D017063:Outcome Assessment, Health Care; D011336:Probability; D012307:Risk Factors