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Moderate/Heavy vs No/Light Exercise Found To Be Effective in Older (age=71) With No Cognitive impairment at Baseline but Not Effective in Those With Cognitive Impairment at Baseline....suggesting pre-symptomatic exercise is recommended "before pathology may become irreversible".
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Average age of study participants was 71, most were Spanish speaking US resident; those who reported moderate/heavy exercise had less diabetes, less hypertension.
DISCUSSION In this racially/ethnically diverse cohort of older adults, we found that, compared to moderate-heavy LTPA, no or low leisure-time physical activity was associated with a greater decline in processing speed among all participants, and episodic memory among those unimpaired at baseline. The degree of decline was equivalent to the expected decline associated with approximately 10 years of cognitive aging.......Our findings inform the role of LTPA in slowing the rate of cognitive decline in the presymptomatic state before pathology may become irreversible.9......Our findings of a lack of a protective effect when we included those who were cognitively impaired are in keeping with results from randomized clinical trials in Alzheimer disease in which LTPA did not affect measures of memory.38
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Leisure-time physical activity associates with cognitive decline
The Northern Manhattan Study
Neurology March 23 2016
Joshua Z. Willey, MD, MS* Hannah Gardener, PhD* Michelle R. Caunca, BS Yeseon Park Moon, MS Chuanhui Dong, PhD Yuen K. Cheung, PhD Ralph L. Sacco, MD, MS Mitchell S.V. Elkind, MD, MS Clinton B. Wright, MD, MS
From the Departments of Neurology (J.Z.W., Y.P.M., M.S.V.E.), Biostatistics (Y.K.C.), and Epidemiology (M.S.V.E.), Columbia University, New York, NY; Departments of Neurology and Public Health Sciences (H.G., M.R.C., C.D., C.B.W., R.L.S.) and Human Genetics (R.L.S.), Miller School of Medicine, University of Miami; and Evelyn F. McKnight Brain Institute (R.L.S., C.B.W.), University of Miami, FL.
Abstract
Objective: Because leisure-time physical activity (LTPA) is protective against incident dementia, we hypothesized that LTPA is protective against decline in domain-specific cognitive performance.
Methods: As part of the Northern Manhattan Study, LTPA was ascertained at enrollment using a validated in-person questionnaire. We assessed cognition in participants in the Northern Manhattan Study MRI substudy using a standard neuropsychological examination (NPE) (n = 1,228), and a repeat examination was performed 5 years later (n = 876). LTPA was summarized as the maximum intensity of any activity performed, classified as none to light intensity (physical inactivity) (90%) vs moderate to heavy intensity (10%). The NPE was subcategorized using standardized z scores over validated domains: processing speed, semantic memory, episodic memory, and executive function. We used multivariable linear regression models to examine the association of LTPA with initial and change in cognitive performance. Analyses were adjusted for sociodemographics, cardiovascular disease risk factors, and MRI findings (white matter hyperintensity volume, silent brain infarcts, cerebral volume).
Results: No/low levels of LTPA were associated with worse executive function, semantic memory, and processing speed scores on the first NPE. The associations were slightly attenuated and no longer significant after adjusting for vascular risk factors. Cognitively unimpaired participants reporting no/low LTPA vs moderate/high levels declined more over time in processing speed (β = −0.231 ± 0.112, p = 0.040) and episodic memory (β = −0.223 ± 0.117, p = 0.057) adjusting for sociodemographic and vascular risk factors.
Conclusions: A low level of LTPA is independently associated with greater decline in cognitive performance over time across domains.
With an expected increase in the mean age and proportion of the population older than 65 years, the public health burden of cognitive impairment and dementia will become substantial.1 There is substantial evidence for a contribution of subclinical cerebrovascular disease to dementia, both through direct vascular injury to the brain and/or modification of neurodegenerative processes. Increasing leisure-time physical activity (LTPA) is one target for dementia prevention because it is modifiable, does not require the use of medications, and provides substantial benefits for other diseases of aging.
Prior studies have shown associations between LTPA and cognitive performance,2-8 and a recent meta-analysis9 has demonstrated a dose-response association between LTPA and subsequent risk of dementia. These studies tend to show a protective effect on only vascular dementia or on Alzheimer disease alone.10,11 Not all groups have documented an association between physical activity and cognition in older individuals.5,12,13 Randomized clinical trials of LTPA programs have shown conflicting results,14-16 with results suggesting improvement in functional but not cognitive status. An NIH State of the Science Statement suggested that there may be a protective effect of LTPA on cognitive decline, based on "low-quality" data.17,18 A Cochrane database review concluded that there is insufficient evidence to support the effect of LTPA on cognitive decline in older people.19
Several gaps in knowledge remain in our understanding of the role LTPA may have on cognitive decline. Most studies used a single measure of cognitive performance obtained at the same time as (or after) the LTPA assessment, rather than a change over time in cognitive scores. These studies also focused on crude
measures of cognitive performance, such as the Mini-Mental State Examination, rather than comprehensive measures of cognition obtained from neuropsychological examinations (NPEs).20 There are few studies on populations older than 65 years and on Spanish speakers residing in the United States. Furthermore, prior studies have not considered the role that cognitive reserve and baseline cognitive impairment may have on subsequent cognitive decline. The aim of this study was to characterize the independent association of LTPA with baseline and change in cognitive performance in a racially/ethnically diverse elderly population. We hypothesized that LTPA would be protective against cognitive decline across multiple domains and that the effect would be modified by baseline crystallized abilities (Gc), an assessment of lifetime intellectual achievement as measured through vocabulary and general knowledge.
Our study is unique in demonstrating that the different effect on decline in processing speed over time between 2 LTPA groups may be more appreciable among those without initial cognitive impairment. This observation is consistent with the paradigm that interventions aimed at preventing cognitive decline need to occur before symptoms are manifest.
Association of LTPA and initial NPE. In models adjusted for baseline demographics at the time of MRI (age, sex, education, insurance, Gc, and time
from baseline to first cognitive assessment), no/light LTPA was associated with worse scores in all cognitive domains compared to moderate- to heavy intensity LTPA, although the association was not statistically significant for episodic memory (table 2). After adjusting for modifiable stroke risk factors and MRI findings, the results attenuated slightly and were no longer significant.
When we examined change in cognitive performance over time, we found similar associations. Participants reporting no/-light LTPA compared to moderate- to heavy-intensity LTPA showed greater decline over time in processing speed, adjusting for sociodemographic and vascular risk factors, but the difference no longer reached significance after adjusting for MRI markers (table 3). For episodic memory, the decline in scores was of a similar magnitude to that seen for processing speed for participants who were physically inactive compared to those reporting moderate-heavy LTPA but this did not reach significance adjusting for sociodemographic and vascular risk factors (p 5 0.057, table 3).
Similar to prior studies in non-Hispanic white populations, our results provide evidence that physical activity may thus delay the onset of cognitive decline, and that effect could be more prominent among those who are cognitively intact at baseline and add to the growing data establishing modifiable risk factors for dementia.32-34
Randomized clinical trials of LTPA [leisure-time physical activity] programs have shown conflicting results,14-16 with results suggesting improvement in functional but not cognitive status.
The aim of this study was to characterize the independent association of LTPA with baseline and change in cognitive performance in a racially/ethnically diverse elderly population. We hypothesized that LTPA would be protective against cognitive decline across multiple domains and that the effect would be modified by baseline crystallized abilities (Gc), an assessment of lifetime intellectual achievement as measured through vocabulary and general knowledge.
Association of LTPA with change in NPE scores excluding those with cognitive impairment at initial NPE. When we excluded participants with evidence of cognitive impairment at initial NPE assessment, participants reporting no/light LTPA declined significantly more in processing speed and episodic memory compared to participants reporting moderate-heavy LTPA adjusting for sociodemographic and vascular risk factors (table 3). After further adjusting for structural MRI findings, the association remained significant for episodic memory (p 5 0.027) but attenuated slightly for processing speed and no longer reached significance (p 5 0.073). The magnitude of the decrease in episodic memory between the 2 NPEs was equivalent to 10 years of aging in our multivariable models (p <0.001).
Baseline characteristics of the cohort are presented in table 1. Our cohort is elderly (mean age = 71 years) with a high proportion of Hispanics and participants who have not completed high school. Participants with 1 vs 2 NPEs did not differ by the measure of LTPA.
The prevalence of participants who reported moderate-heavy physical activity was 10%. The scores on the NPE declined between the first and second examination in all 4 domains, with a slightly greater decline in processing speed compared to other domains.
Several gaps in knowledge remain in our understanding of the role LTPA may have on cognitive decline. Most studies used a single measure of cognitive performance obtained at the same time as (or after) the LTPA assessment, rather than a change over time in cognitive scores. These studies also focused on crude measures of cognitive performance, such as the Mini-Mental State Examination, rather than comprehensive measures of cognition obtained from neuropsychological examinations (NPEs).20 There are few studies on populations older than 65 years and on Spanish speakers residing in the United States. Furthermore, prior studies have not considered the role that cognitive reserve and baseline cognitive impairment may have on subsequent cognitive decline.
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