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1.  Survival in Older Men May Benefit From Being Slightly Overweight and Centrally Obese—A 5-Year Follow-up Study in 4,000 Older Adults Using DXA 
Whether overweight in old age is hazardous remains controversial. Body mass index (BMI) overestimates adiposity and fails to measure central adiposity. We used dual-energy x-ray absorptiometry (DXA) to measure adiposity and hypothesized that overall adiposity, distribution of adiposity, and muscle mass might individually affect survival.
We recruited 2000 men and 2000 women aged 65 years or older. Baseline BMI, waist–hip ratio (WHR), body fat index (BFI = total body fat/height square), relative truncal fat (RTF = trunk fat/total body fat), and body muscle mass index (BMMI = total body muscle mass/height square) were measured. Mortality was ascertained by death registry after 63.3 (median) months.
Two hundred and forty-two men and 78 women died. In men, mortality hazard ratio (HR) decreased consistently by 0.85 (p < .005), 0.86 (p < .005), and 0.86 (p < .005) per every quintile increase in BMI, BFI, and BMMI, respectively. A J-shaped relationship was observed in central adiposity (RTF and WHR) quintiles; the minimum values were at the 3rd WHR quintile (0.92–0.94) and 4th RTF quintile (mean WHR, 0.94). When RTF was tested with BFI, both high and low central adiposity were unfavorable while general adiposity became marginally insignificant (p = 0.062). When BFI and BMMI were tested together, increasing adiposity rather than muscle mass favored survival (BFI quintile, HR 0.97, p .015; BMMI quintile, HR 1.00, p .997).
Older men were resistive to hazards of overweight and adiposity; and mild-grade overweight, obesity, and even central obesity might be protective. This may bear significant implication on the recommended cutoff values for BMI and WHR in the older population.
PMCID: PMC2796879  PMID: 19628635
mortality; adiposity; BMI; muscles
2.  Functional Decline in Cognitive Impairment – The Relationship between Physical and Cognitive Function 
Neuroepidemiology  2008;31(3):167-173.
Physical function decline is associated with dementia, which might either be mediated by the coexisting sarcopenia or directly related to the impaired cognition. Our objectives are to examine the relationship between cognitive function and performance-based physical function and to test the hypothesis that cognitive function is related to poor physical function independent of muscle mass.
We measured muscle strength, performance-based physical function and muscle mass using dual-energy X-ray absorptiometry and cognitive function using the cognitive part of the Community Screening Instrument of Dementia (CSI-D) in 4,000 community-dwelling Chinese elderly aged >65 years. A CSI-D cognitive score of >28.40 was considered as cognitively impaired. The effect of cognitive impairment on muscle strength and physical function was analyzed by multivariate analysis with adjustment for age, appendicular skeletal mass (ASM), the Physical Activity Scale for the Elderly (PASE) and other comorbidities.
In both genders, the cognitively impaired (CSI-D cognitive score >28.40) group had a weaker grip strength (–5.10 kg, p < 0.001 in men; −1.08 kg in women, p < 0.001) and performed worse in the two physical function tests (in men, 6-meter walk speed, −0.13 m/s, p < 0.001, chair stand test, 1.42 s, p < 0.001; in women, 6-meter walk speed, −0.08 m/s, p < 0.001, chair stand test, 1.48 s, p < 0.001). After adjustment for age, ASM, PASE and other comorbidities, significant differences in grip strength (–2.60 kg, p < 0.001 in men; −0.49 kg, p = 0.011 in women) and the two physical function tests persisted between the cognitively impaired and nonimpaired group (in men, 6-meter walk speed, −0.072 m/s, p < 0.001, chair stand test, 0.80 s, p = 0.045; in women, 6-meter walk speed, −0.049 m/s, p < 0.001, chair stand test, 0.98 s, p < 0.001).
Poor physical function and muscle strength coexisted with cognitive impairment. This relationship was independent of muscle mass. It is likely therefore that the functional decline in dementia might be related directly to factors resulting in cognitive impairment independently of the coexisting sarcopenia.
PMCID: PMC2824577  PMID: 18784415
Sarcopenia; Dementia; Cognition; Chinese elderly; Physical function; Muscle
3.  Adiposity to muscle ratio predicts incident physical limitation in a cohort of 3,153 older adults—an alternative measurement of sarcopenia and sarcopenic obesity 
Age  2012;35(4):1377-1385.
Conventionally, sarcopenia is defined by muscle mass and physical performance. We hypothesized that the disability caused by sarcopenia and sarcopenic obesity was related to the amount of adiposity or body weight bearing on a unit of muscle mass, or the adiposity to muscle ratio. We therefore examined whether this ratio could predict physical limitation by secondary analysis of the data in our previous study. We recruited 3,153 community-dwelling adults aged >65 years and their body composition was measured by dual-energy X-ray absorptiometry. Assessment of physical limitation was undertaken 4 years later. The relationship between baseline adiposity to muscle ratio and incident physical limitation was examined by logistic regression. In men, the adiposity to muscle ratios, namely total body fat to lower-limb muscle mass, total body fat to fat-free mass (FFM), and body weight to FFM, were predictive of physical limitation before and after adjustment for the covariates: age, Mini-mental Status Examination score, Geriatric Depression Scale score >8, and the diagnosis of chronic obstructive pulmonary disease, diabetes mellitus, hypertension, heart disease, and stroke (all p values < 0.001), when the total body fat to lower-limb muscle mass ratio was greater than or equal to 0.75. In women, throughout the entire range of that ratio, all three adiposity to muscle ratios were associated with physical limitation 4 years later both before and after adjustment for the same set of covariates (all p values < 0.05). Sarcopenia and sarcopenic obesity as measured by the body weight or adiposity bearing on a unit of muscle mass (the adiposity to muscle ratio) could predict incident or worsening physical limitation in older women across the entire range of the total body fat to lower-limb muscle mass ratio; and in older men when this ratio was equal to or greater than 0.75.
PMCID: PMC3705102  PMID: 22614096
Sarcopenia; Sarcopenic obesity; Elderly; Muscle mass; Fat mass; Physical limitations
4.  Cognitive deficit is associated with phase advance of sleep–wake rhythm, daily napping, and prolonged sleep duration—a cross-sectional study in 2,947 community-dwelling older adults 
Age  2012;35(2):479-486.
This study aims to examine the phase advance of sleep–wake rhythm, napping habit, nocturnal sleep duration, prolonged sleep latency and insomnia and their relationship with cognitive function. This is a cross-sectional study. Participants in this study are 2,947 community-dwelling adults older than 65 years old. Measurements of mini-mental examination (MMSE) score, go-to-bed time, wake-up time, nocturnal sleep duration, prolonged sleep latency, napping, and insomnia were done. The mean (standard deviation) nocturnal sleep hours was 7.96 (1.39) h. Twenty-one percent and 16.2% of the participants complained of prolonged sleep latency longer than 1 h and insomnia, respectively. Fifty-six percent of the participants napped once or more than once weekly. With advancing age, the participants reported longer sleep duration (p < 0.001), went to bed earlier, and woke up earlier, which were significant both before and after adjustment. The participants who had lower MMSE score went to bed earlier and woke up earlier, which were statistically significant both before and after adjustment. An inverted U-shaped relationship was observed between MMSE score and napping frequency, p for tend 0.026.The MMSE score decreased when the sleep duration prolonged from 7 h to ≧10 h (p for trend 0.006). No trend was observed from the sleep duration <4 up to 7.9 h (p for trend 0.500). Modest age-independent phase advance of the sleep–wake rhythm is associated with lower cognitive function. Whether this is a manifestation of early pre-clinical dementia and whether its recognition with early stabilization can slow cognitive decline remain elusive.
PMCID: PMC3592949  PMID: 22215376
Phase advance; Sleep/wake rhythm; Sleep duration; Dementia; Cognitive decline; Napping; Insomnia; Prolonged sleep latency
5.  Survival benefit of abdominal adiposity: a 6-year follow-up study with Dual X-ray absorptiometry in 3,978 older adults 
Age  2011;34(3):597-608.
In contrast to that in the middle-aged, higher body mass index (BMI) in older people is associated with higher survival rates. Yet, BMI makes no distinction between fat elsewhere and abdominal fat, the latter being metabolically more harmful. We hypothesized that overall adiposity might be protective in old age, but that central fat might offset that benefit and remained harmful as in the middle-aged. Three thousand nine hundred seventy-eight Chinese elderly ≥65 years had demographics, medical conditions, physical activity, and body composition by DXA recorded at baseline. Overall adiposity was measured as whole body fat%, and abdominal adiposity as waist circumference, waist–hip ratio, and relative abdominal fat (RAF) (relative abdominal fat = abdominal fat according to anatomical landmarks/whole body fat). Deaths within 1 year from baseline were excluded from analysis. All-cause and cardiovascular mortality were analyzed using Cox regression, adjusted for covariates. The lowest quintile of adiposity measurements was used for comparison. After a mean follow-up of 72.3 months, 13.7% men and 4.5% women had died. In men, the highest two quintiles of whole body fat % and the upper four quintiles of RAF were associated with significantly lower all-cause mortality, and adjusted hazard ratio (95% CI) in ascending quintiles of RAF compared with the lowest quintile was 0.62 (0.43–0.89), 0.58 (0.4–0.85), 0.52 (0.36–0.77), and 0.67 (0.47–0.96). No relationship was found between abdominal adiposity and cardiovascular mortality in both genders. Higher whole body fat % as well as higher proportion of abdominal fat was associated with lower all-cause mortality in men. No such relation was found in women.
PMCID: PMC3337922  PMID: 21667162
Central adiposity; Obesity; Elderly; Mortality; Life Sciences; Molecular Medicine; Geriatrics/Gerontology; Cell Biology
6.  Effects of height loss on morbidity and mortality in 3145 community-dwelling Chinese older women and men: a 5-year prospective study 
Age and Ageing  2010;39(6):699-704.
Background: height loss beginning in mid-life and post-menopausal period was associated with adverse health outcomes. However, height loss occurring after old age has been little studied. We examined how height loss was related to bone mineral density (BMD) change, fracture incidence and cause-specific mortality in older adults.
Methods: the stature and BMD of 3145 community-dwelling men and women aged ≥65 were measured at baseline and after 4 years. All fracture and cause-specific mortality events were searched in a territory-wide clinical information database and death registry.
Results: twenty-five (1.6%) men and 64 (4.0%) women lost >2 cm after 4 years. In women, the BMD decline was faster in the rapid height losers (adjusted difference = 4.18%, P < 0.001). There was no corresponding difference observed in men. Rapid height loss was associated with excess all fractures and hip fractures (adjusted HR for all fractures = 2.86, P < 0.001; adjusted HR for hip fractures = 4.74, P < 0.01) in women but only hip fractures (adjusted HR = 4.93, P < 0.05) in men. The all-cause (adjusted HR = 3.43, P < 0.01) and respiratory disease mortality (adjusted HR = 5.64, P < 0.05) were higher in men with rapid height loss, whereas those in women were insignificant.
Conclusions: modest height loss occurring after old age, >2 cm in 4 years, was associated with excess hip fracture, total and respiratory disease mortality in older men. In women, it was associated with excess BMD decline, all fractures and hip fractures but not mortality. Further research is needed to determine the usefulness of regular stature measurement as an indicator of bone health in the primary-care setting in older adults.
PMCID: PMC2956531  PMID: 20817934
height loss; mortality; fractures; osteoporosis; elderly

Results 1-6 (6)