Misti L. Paudel

Circadian activity rhythms and risk of incident dementia and mild cognitive impairment in older women.

Previous cross‐sectional studies have observed alterations in activity rhythms in dementia patients but the direction of causation is unclear. We determined whether circadian activity rhythms measured in community‐dwelling older women are prospectively associated with incident dementia or mild cognitive impairment (MCI).

25-Hydroxyvitamin D levels and cognitive performance and decline in elderly men

Objective: To test the hypothesis that lower 25-hydroxyvitamin D [25(OH)D] levels are associated with a greater likelihood of cognitive impairment and risk of cognitive decline. Methods: We measured 25(OH)D and assessed cognitive function using the Modified Mini-Mental State Examination (3MS) and Trail Making Test Part B (Trails B) in a cohort of 1,604 men enrolled in the Osteoporotic Fractures in Men Study and followed them for an average of 4.6 years for changes in cognitive function. Results: In a model adjusted for age, season, and site, men with lower 25(OH)D levels seemed to have a higher odds of cognitive impairment, but the test for trend did not reach significance (impairment by 3MS: odds ratio [OR] 1.84, 95% confidence interval [CI] 0.81–4.19 for quartile [Q] 1; 1.41, 0.61–3.28 for Q2; and 1.18, 0.50–2.81 for Q3, compared with Q4 [referent group; p trend = 0.12]; and impairment by Trails B: OR 1.66, 95% CI 0.98–2.82 for Q1; 0.96, 0.54–1.69 for Q2; and 1.30, 0.76–2.22 for Q3, compared with Q4 [p trend = 0.12]). Adjustment for age and education further attenuated the relationships. There was a trend for an independent association between lower 25(OH)D levels and odds of cognitive decline by 3MS performance (multivariable OR 1.41, 95% CI 0.89–2.23 for Q1; 1.28, 0.84–1.95 for Q2; and 1.06, 0.70–1.62 for Q3, compared with Q4 [p = 0.10]), but no association with cognitive decline by Trails B. Conclusion: We found little evidence of independent associations between lower 25-hydroxyvitamin D level and baseline global and executive cognitive function or incident cognitive decline.

Bone mass and strength in older men with type 2 diabetes: The Osteoporotic Fractures in Men Study

The effects of type 2 diabetes mellitus (T2DM) on bone volumetric density, bone geometry, and estimates of bone strength are not well established. We used peripheral quantitative computed tomography (pQCT) to compare tibial and radial bone volumetric density (vBMD, mg/cm3), total (ToA, mm2) and cortical (CoA, mm2) bone area and estimates of bone compressive and bending strength in a subset (n = 1171) of men (≥65 years of age) who participated in the multisite Osteoporotic Fractures in Men (MrOS) study. Analysis of covariance–adjusted bone data for clinic site, age, and limb length (model 1) and further adjusted for body weight (model 2) were used to compare data between participants with (n = 190) and without (n = 981) T2DM. At both the distal tibia and radius, patients with T2DM had greater bone vBMD (+2% to +4%, model 1, p < .05) and a smaller bone area (ToA −1% to −4%, model 2, p < .05). The higher vBMD compensated for lower bone area, resulting in no differences in estimated compressive bone strength at the distal trabecular bone regions. At the mostly cortical bone midshaft sites of the radius and tibia, men with T2DM had lower ToA (−1% to −3%, p < .05), resulting in lower bone bending strength at both sites after adjusting for body weight (−2% to −5%, p < .05) despite the lack of difference in cortical vBMD at these sites. These data demonstrate that older men with T2DM have bone strength that is low relative to body weight at the cortical‐rich midshaft of the radius despite no difference in cortical vBMD.

Association Between Depressive Symptoms and Sleep Disturbances in Community-Dwelling Older Men

OBJECTIVES: To examine the association between depressive symptoms and subjective and objective measures of sleep in community‐dwelling older men.

Sleep Disturbances and Frailty Status in Older Community-Dwelling Men

OBJECTIVES: To test the hypothesis that sleep disturbances are independently associated with frailty status in older men.

Serum 25-Hydroxyvitamin D Levels and Rate of Hip Bone Loss in Older Men

CONTEXT Vitamin D deficiency is common among older adults, but the association between 25-hydroxyvitamin D [25(OH)D] levels and rates of bone loss is uncertain. OBJECTIVE Our aim was to test the hypothesis that lower 25(OH)D levels are associated with higher rates of hip bone loss in older men. DESIGN AND SETTING We conducted a prospective cohort study in six U.S. centers. PARTICIPANTS A total of 1279 community-dwelling men aged 65 yr or older with 25(OH)D levels (liquid chromatography-tandem mass spectroscopy) and hip bone mineral density (BMD) (dual-energy x-ray absorptiometry) at baseline and repeat hip BMD an average of 4.4 yr later participated in the study. MAIN OUTCOME MEASURE(S) We measured the annualized percentage rate of change in hip BMD. RESULTS After adjustment for multiple potential confounders, the average rate of decline in total hip BMD was -0.59%/yr among men with 25(OH)D levels below 15.0 ng/ml, -0.54%/yr among men with 25(OH)D levels 15.0-19.9 ng/ml, -0.35%/yr among men with 25(OH)D levels 20.0-29.9 ng/ml, and -0.37%/yr among men with 25(OH)D levels of at least 30 ng/ml (P trend = 0.008 for multivariable model). Evidence was strong to support an association among men aged 75 yr and older (P trend <0.001), but not among younger men (P trend = 0.55). Findings were similar when 25(OH)D level was expressed in quintiles and when BMD at hip subregions was substituted for total hip BMD. CONCLUSIONS In this cohort of community-dwelling older men, men with 25(OH)D levels below 20 ng/ml had greater subsequent rates of hip bone loss, but rates of loss were similar among men with higher levels. These results lend support to the view that low 25(OH)D levels are detrimental to BMD in older men.

Kidney Function and Cognitive Performance and Decline in Older Men

OBJECTIVES: To examine the association between kidney function and cognitive impairment and decline in elderly men.

Sleep Disturbances and Risk of Frailty and Mortality in Older Men

OBJECTIVE To test the hypothesis that non-frail older men with poorer sleep at baseline are at increased risk of frailty and death at follow-up. METHODS In this prospective cohort study, subjective (questionnaires) and objective sleep parameters (actigraphy, in-home overnight polysomnography) were measured at baseline in 2505 non-frail men aged ≥67years. Repeat frailty status assessment performed an average of 3.4 years later; vital status assessed every four months. Sleep parameters expressed as dichotomized predictors using clinical cut-points. Status at follow-up exam classified as robust, intermediate (pre-frail) stage, frail, or died in interim. RESULTS None of the sleep disturbances were associated with the odds of being intermediate/frail/dead (vs. robust) at follow-up. Poor subjective sleep quality (multivariable odds ratio [MOR] 1.26, 95% CI 1.01-1.58), greater nighttime wakefulness (MOR 1.31, 95% CI 1.04-1.66), and greater nocturnal hypoxemia (MOR 1.47, 95% CI 1.02-2.10) were associated with a higher odds of frailty/death at follow-up (vs. robust/intermediate). Excessive daytime sleepiness (MOR 1.60, 95% CI 1.03-2.47), greater nighttime wakefulness (MOR 1.57, 95% CI 1.12-2.20), severe sleep apnea (MOR 1.74, 95% CI 1.04-2.89), and nocturnal hypoxemia (MOR 2.28, 95% CI 1.45-3.58) were associated with higher odds of death (vs. robust/intermediate/frail at follow-up). The association between poor sleep efficiency and mortality nearly reached significance (MOR 1.48, 95% CI 0.99-2.22). Short sleep duration and prolonged sleep latency were not associated with frailty/death or death at follow-up. CONCLUSIONS Among non-frail older men, poor subjective sleep quality, greater nighttime wakefulness, and greater nocturnal hypoxemia were independently associated with higher odds of frailty or death at follow-up, while excessive daytime sleepiness, greater nighttime wakefulness, severe sleep apnea and greater nocturnal hypoxemia were independently associated with an increased risk of mortality.

Depressive Symptoms and Subjective And Objective Sleep In Community-Dwelling Older Women

To examine the relationship between depressive symptoms and subjective and objective sleep in older women.

Muscle power and physical activity are associated with bone strength in older men: The osteoporotic fractures in men study

The purpose of these analyses was to explore whether physical activity score, leg power or grip strength were associated with tibia and radius estimates of bone strength, cortical density, or total bone area. Peripheral quantitative computed tomography (pQCT) was used to compare tibial and radial bone volumetric density (vBMD, mg/cm(3)), total (ToA, mm(2)) and cortical (CoA, mm(2)) bone area, and estimates of bone compressive strength (bone strength index, BSI) and bending strength (polar strength strain index, SSIp) in a subset (n=1171) of men (> or = 65 years) who participated in the multi-site Osteoporotic Fractures in Men (MrOS) study. Physical activity was assessed by questionnaire (PASE), leg power by Nottingham Power Rig, and grip strength by a hand-held Dynamometer. Participants were categorized into quartiles of PASE, grip strength or leg power. The model was adjusted for age, race, clinic, weight, and limb length. In the tibia, BSI (+7%) and SSIp (+4%) were highest in the most active physically quartile compared to the least active (p<0.05). At the 4% site of the tibia, men with the greatest leg power had both greater ToA (+5%, p<0.001) and BSI (+5.3%, p=0.086) compared to men with the least leg power. At the 66% site of the tibia, the men with the highest leg power, compared to the men with the lowest leg power, had greater ToA (+3%, p=0.045) SSIp (+5%, p=0.008). Similar results were found at both the distal and midshaft of the radius. The findings of this study suggest the importance of maintaining levels of physical activity and muscle strength in older men to prevent bone fragility.