- Email: [email protected]
P4-123: A multistate model of transitions in cognitive function in elderly people
Poster Presentations P4: Weighted analyses, which account for selection bias, suggest substantially increased risk: RR 4.37; 95% CI 2.07, 9.24. Unadjusted analyses further suggest no evidence of an association between cortical Lewy bodies and dementia (RR 1.64; 95% CI 0.78, 3.47). Weighted analyses suggest increased risk; RR 2.36; 95% 1.24, 4.52. Additional analyses indicate little sensitivity in the results provided dementia status, age, gender and race are included in a model for the weights. Conclusions: Care must be taken to account for well-documented sources of selection bias in neuropathological studies; weighted regression analyses provide a means to establish generalizability beyond an autopsied sample. For the ACT study, a weighted analysis identifies an association of cortical Lewy bodies and dementia that was missed when selection bias is ignored. P4-121
TWELVE YEAR TRAJECTORIES OF COGNITIVE DECLINE IN ELDERLY AFRICAN AMERICANS
Hugh C. Hendrie1, Kathleen Lane2, Su Gao2, Frederick Unverzagt3, Jill R. Murrell4, Valerie Smith-Gamble5, Olesugen Baiyewu6, Kathleen S. Hall7, 1Indiana University Center for Aging Research, Indianapolis, IN, USA; 2Indiana University School of Medicine/Department of Medicine, Indianapolis, IN, USA; 3Indiana University School of Medicine/Department of Psychiatry, Indianapolis, IN, USA; 4Indiana University School of Medicine/Department of Pathology, Indianapolis, IN, USA; 5Indiana University School of Medicine/Verteran’s Administration Medical Center, Indianapolis, IN, USA; 6University of Ibadan/Department of Psychiatry, Ibadan, Nigeria; 7 Indiana University School of Medicine/Department of Psychiatry, Indianapolis, IN, USA. Contact e-mail: [email protected] Background: As part of the Indianapolis-Ibadan dementia project, cognitive decline was monitored over 12 years. Methods: 1703 community-dwelling African Americans 65 yrs and over who were neither demented nor cognitively impaired at baseline. A total of 4 follow up evaluations were conducted after baseline. Only subjects who had a follow up evaluation were included in this analysis. Cognitive decline was evaluated using the CSI”D”, an instrument designed for use in literate and non-literate populations. It was constructed to measure ICD and DSM criteria for dementia. The cognitive portion contains a total of 56 items, measuring memory (28 items), semantic memory (language, 12 items) and executive function (16 items). Results: During the 12 years of follow-up, 165 subjects developed incident dementia, 160 developed incident CIND, and 1378 remained not cognitively impaired. As might be anticipated subjects who developed incident demented showed the greatest cognitive decline compared to that of the noncognitively impaired subjects with the CIND subjects occupying an intermediate position. Significant cognitive decline occurred over the 12 year period for the not cognitively impaired subjects even after excluding the incident dementia and CIND subjects and occurred in all 3 cognitive domains (memory, and executive p-values ⬍0.0001; semantic p-value 0.0130). Increasing age was also significantly associated with cognitive decline for all domains. (p⬍0.0001). Conclusions: Significant cognitive decline was observed in all subjects in this large cohort of community-dwelling African Americans regardless of outcome status and across all cognitive domains. The semantic domain showed the least decline. The implications of these results will be discussed. P4-122
CHANGES IN COGNITION IN RELATION TO EXERCISE IN LATE LIFE
Laura E. Middleton, Arnold Mitnitski, Nadar Fallah, Susan Kirkland, Kenneth Rockwood, Dalhousie University, Halifax, NS, Canada. Contact e-mail: [email protected] Background: On average, cognition declines with age but this average hides variability; with exercise, there is not only less risk of cognitive
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decline but also a chance of improvement, although typically this has received less attention.Our objective here is to study how exercise influences cognition in elderly people and to consider whether the mortality benefit of exercise might offset gains in cognition by allowing more people to live longer, increasing their dementia risk. Methods: In the Canadian Study of Health and Aging, of 8403 people at CSHA-1, 5376 were re-examined at CSHA-2 and 2219 died. We estimated the probabilities of cognitive improvement, deterioration, and death from any cognitive state, adjusted for education and age. Results: People who exercised more had more chance of having stable or improved cognition (37.5%) than did others (18.3%). The difference was enhanced as baseline cognition worsened. The proportion that declined, however, was much more similar (34.8% for the high exercise group and 39.4% for the low/no exercise group), with no significant difference between groups. Across all cognitive states, people who did not exercise had higher risk of mortality (42.3% versus 27.8%). Exercise conferred its greatest benefit to mortality amongst people with the highest cognition at baseline. Conclusions: Exercise is strongly associated with improving cognitive health. As the majority of mortality benefit of exercise is seen most at the highest level of cognition, and declines as cognition declines, the net effect of exercise should be to improve cognition at the population level, even with more people living longer. P4-123
A MULTISTATE MODEL OF TRANSITIONS IN COGNITIVE FUNCTION IN ELDERLY PEOPLE
Arnold B. Mitnitski1, Nader Fallah1, Charmaine B. Dean2, Kenneth Rockwood1, 1Dalhousie University, Halifax, NS, Canada; 2 Simon Fraser University, Vancouver, BC, Canada. Contact e-mail: [email protected] Background: On average, cognitive functions worsen with age, but many people have periods of improvement. Whether the changes are inevitable, and somehow benign, or the beginning of a decline that will be seen as pathologic is not clear. We present a multi-state Markov model to summarize five-year transitions in cognitive function in elderly Canadians and analyze how known risk factors influence such transitions. Methods: 2,199 elderly Canadians (65⫹) followed-up for two consecutive five- year intervals as part of the Canadian Study of Health and Aging. Cognitive status is assessed by the 100-point Modified Mini-Mental State Examination (3MS) score. The model is based on a parametric representation of the probabilities of transitions between different cognitive states represented by the number of errors on the 3MS to estimate the probabilities of transitions in different directions: improvements, declines, and death as. The basic model is characterized by four parameters, two of which represent cognitive transitions in survivors. The other two represent the likelihood of death. Results: The probabilities of five-year improvements, worsening and dying as a function of the current state of cognition and two covariates (age and sex) are estimated. The performance of the model is very high - the correlation coefficient between the observed data and the models’ fit lies between 0.92and 0.96. Both sex and age influence transitions to death significantly associated with the probability of death. Relatively large number of people (about 30%) show “back transitions” -getting better or remaining stable. The relative risk of dying calculated for younger men versus younger women is 3.8 (at zero state -no cognitive errors) and gradually diminishes for the people with increasing cognitive errors at baseline (to 1.4) while the relative risks for older men versus older women almost does not changes (from 1.4 to 1.2). The relative risk of dying for older versus younger women changes from 4.0 to 1.4, and for men does not change much (from 1.5 to 1.7). Conclusions: This model suggests that all transitions, including improvement, worsening, and death can be summarized in a simple stochastic model with a few interpretable parameters.
TWELVE YEAR TRAJECTORIES OF COGNITIVE DECLINE IN ELDERLY AFRICAN AMERICANS
Hugh C. Hendrie1, Kathleen Lane2, Su Gao2, Frederick Unverzagt3, Jill R. Murrell4, Valerie Smith-Gamble5, Olesugen Baiyewu6, Kathleen S. Hall7, 1Indiana University Center for Aging Research, Indianapolis, IN, USA; 2Indiana University School of Medicine/Department of Medicine, Indianapolis, IN, USA; 3Indiana University School of Medicine/Department of Psychiatry, Indianapolis, IN, USA; 4Indiana University School of Medicine/Department of Pathology, Indianapolis, IN, USA; 5Indiana University School of Medicine/Verteran’s Administration Medical Center, Indianapolis, IN, USA; 6University of Ibadan/Department of Psychiatry, Ibadan, Nigeria; 7 Indiana University School of Medicine/Department of Psychiatry, Indianapolis, IN, USA. Contact e-mail: [email protected] Background: As part of the Indianapolis-Ibadan dementia project, cognitive decline was monitored over 12 years. Methods: 1703 community-dwelling African Americans 65 yrs and over who were neither demented nor cognitively impaired at baseline. A total of 4 follow up evaluations were conducted after baseline. Only subjects who had a follow up evaluation were included in this analysis. Cognitive decline was evaluated using the CSI”D”, an instrument designed for use in literate and non-literate populations. It was constructed to measure ICD and DSM criteria for dementia. The cognitive portion contains a total of 56 items, measuring memory (28 items), semantic memory (language, 12 items) and executive function (16 items). Results: During the 12 years of follow-up, 165 subjects developed incident dementia, 160 developed incident CIND, and 1378 remained not cognitively impaired. As might be anticipated subjects who developed incident demented showed the greatest cognitive decline compared to that of the noncognitively impaired subjects with the CIND subjects occupying an intermediate position. Significant cognitive decline occurred over the 12 year period for the not cognitively impaired subjects even after excluding the incident dementia and CIND subjects and occurred in all 3 cognitive domains (memory, and executive p-values ⬍0.0001; semantic p-value 0.0130). Increasing age was also significantly associated with cognitive decline for all domains. (p⬍0.0001). Conclusions: Significant cognitive decline was observed in all subjects in this large cohort of community-dwelling African Americans regardless of outcome status and across all cognitive domains. The semantic domain showed the least decline. The implications of these results will be discussed. P4-122
CHANGES IN COGNITION IN RELATION TO EXERCISE IN LATE LIFE
Laura E. Middleton, Arnold Mitnitski, Nadar Fallah, Susan Kirkland, Kenneth Rockwood, Dalhousie University, Halifax, NS, Canada. Contact e-mail: [email protected] Background: On average, cognition declines with age but this average hides variability; with exercise, there is not only less risk of cognitive
T705
decline but also a chance of improvement, although typically this has received less attention.Our objective here is to study how exercise influences cognition in elderly people and to consider whether the mortality benefit of exercise might offset gains in cognition by allowing more people to live longer, increasing their dementia risk. Methods: In the Canadian Study of Health and Aging, of 8403 people at CSHA-1, 5376 were re-examined at CSHA-2 and 2219 died. We estimated the probabilities of cognitive improvement, deterioration, and death from any cognitive state, adjusted for education and age. Results: People who exercised more had more chance of having stable or improved cognition (37.5%) than did others (18.3%). The difference was enhanced as baseline cognition worsened. The proportion that declined, however, was much more similar (34.8% for the high exercise group and 39.4% for the low/no exercise group), with no significant difference between groups. Across all cognitive states, people who did not exercise had higher risk of mortality (42.3% versus 27.8%). Exercise conferred its greatest benefit to mortality amongst people with the highest cognition at baseline. Conclusions: Exercise is strongly associated with improving cognitive health. As the majority of mortality benefit of exercise is seen most at the highest level of cognition, and declines as cognition declines, the net effect of exercise should be to improve cognition at the population level, even with more people living longer. P4-123
A MULTISTATE MODEL OF TRANSITIONS IN COGNITIVE FUNCTION IN ELDERLY PEOPLE
Arnold B. Mitnitski1, Nader Fallah1, Charmaine B. Dean2, Kenneth Rockwood1, 1Dalhousie University, Halifax, NS, Canada; 2 Simon Fraser University, Vancouver, BC, Canada. Contact e-mail: [email protected] Background: On average, cognitive functions worsen with age, but many people have periods of improvement. Whether the changes are inevitable, and somehow benign, or the beginning of a decline that will be seen as pathologic is not clear. We present a multi-state Markov model to summarize five-year transitions in cognitive function in elderly Canadians and analyze how known risk factors influence such transitions. Methods: 2,199 elderly Canadians (65⫹) followed-up for two consecutive five- year intervals as part of the Canadian Study of Health and Aging. Cognitive status is assessed by the 100-point Modified Mini-Mental State Examination (3MS) score. The model is based on a parametric representation of the probabilities of transitions between different cognitive states represented by the number of errors on the 3MS to estimate the probabilities of transitions in different directions: improvements, declines, and death as. The basic model is characterized by four parameters, two of which represent cognitive transitions in survivors. The other two represent the likelihood of death. Results: The probabilities of five-year improvements, worsening and dying as a function of the current state of cognition and two covariates (age and sex) are estimated. The performance of the model is very high - the correlation coefficient between the observed data and the models’ fit lies between 0.92and 0.96. Both sex and age influence transitions to death significantly associated with the probability of death. Relatively large number of people (about 30%) show “back transitions” -getting better or remaining stable. The relative risk of dying calculated for younger men versus younger women is 3.8 (at zero state -no cognitive errors) and gradually diminishes for the people with increasing cognitive errors at baseline (to 1.4) while the relative risks for older men versus older women almost does not changes (from 1.4 to 1.2). The relative risk of dying for older versus younger women changes from 4.0 to 1.4, and for men does not change much (from 1.5 to 1.7). Conclusions: This model suggests that all transitions, including improvement, worsening, and death can be summarized in a simple stochastic model with a few interpretable parameters.