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P3‐161: Changes in cognition in relation to frailty in older Canadians
Author(s) -
Mitnitski Arnold B.,
Fallah Nader,
Rockwood Kenneth
Publication year - 2009
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2009.04.1035
Subject(s) - cognition , cognitive decline , gerontology , dementia , demography , medicine , poisson regression , frailty index , effects of sleep deprivation on cognitive performance , psychology , disease , psychiatry , population , sociology
Background: On average, cognition declines with age, but more rapidly in some groups than in others. In individuals, cognition can even improve, although this is often viewed simply as diagnostic unreliability. Widely used models focus on a small number of outcomes, (e.g. worse /not worse, dead / alive). By contrast, multistate transition models allow simultaneous consideration of many outcomes including mortality. Methods: We analyzed two, four, six and eight-year cognitive changes and mortality with a novel multistate model. Its performance is illustrated with standard risk factors in a cohort of Japanese Americans living in King County, The Kame Project (n1⁄41985). Cognitive states were defined by errors in the Cognitive Abilities Screening Instrument score. Successive cognitive states from high cognition/low errors to impaired cognition/high errors errors were grouped by 2’s, an analytically detectable interval. Transition probabilities were modeled using the Poisson model with the Poisson mean and mortality both dependent on the cognitive state, and covariates: age, sex, and APOE genotype. Results: After two years, the probability of improvement was 29.3% (95% CI1⁄427%-31.6%); the probability of remaining stable was 22.3% (20.1%24.4%); that of getting worse was 39.1% (36.6%-41.5%). The probability of death was 8.8% (7.4%-10.2%). After 8 years, the chance of dying was 24.4% (22.3%-26.5%), whereas the chance of cognitive worsening, stability and improvement did not change as much: 24.7% (22.5%-26.8%), 17.7% (15.8%-19.6%), and 33.2% (30.8%-35.5%) respectively. In multivariable analyses, age, sex and education were independently associated with cognitive changes, improvements were more likely among younger, more educated people and in women. Conclusions: A multistate transition model can estimate the impact of common covariates on the individual probabilities of cognitive improvement, stability decline and death. Especially with public health initiatives aimed at preventing dementia, such an approach can reveal novel patterns of change in response to interventions.