Dementia and dependence
Do modifiable risk factors delay disability?
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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.
GLOSSARY
- ADL=
- activities of daily living;
- CI=
- confidence interval;
- DSM-III-R=
- Diagnostic and Statistical Manual of Mental Disorders, 3rd edition, revised;
- DSM-IV=
- Diagnostic and Statistical Manual of Mental Disorders, 4th edition;
- HRS=
- Health and Retirement Study;
- IPW=
- inverse probability weighting;
- OR=
- odds ratio
Footnotes
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Supplemental data at Neurology.org
- Received June 29, 2013.
- Accepted in final form January 28, 2014.
- © 2014 American Academy of Neurology
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