Objectives To elucidate the mechanism through which vitamin D is associated with decreased falls. Design This was a convenience sample from a larger observational study examining correlations between vitamin D and 1) falls, 2) motor function, and 3) cognition (n=159). Setting Falls data were collected via weekly on-line surveys completed in the participants' homes. Yearly evaluations of motor and cognitive function were conducted in an out-patient setting of a large tertiary medical center. Participants Participants from the Intelligent Systems for Assessment of Aging Changes Study (ISAAC), a community-based cohort study of independently living older adults over age 70, who had vitamin D concentration within 6 months of clinical evaluations were included in the analysis. Results Participants mean age was 85 years and 74% were women. Fallers (n=37) had significantly lower vitamin D concentration (32.9 ng/ml) compared to non-fallers (39.2 ng/ml) (p<0.01). The relationship between vitamin D and falls remained significant after adjusting for age, health status (via CIRS), and supplement use (p=0.004). Vitamin D concentration were significantly associated with cognitive impairment (Clinical Dementia Rating = 0.5) (p=0.02) and MMSE (p<0.01) after adjusting for age, gender, and education. Vitamin D concentrations did not correlate with any motor measures. Conclusion Vitamin D concentrations correlated with cognition and falls, but not with motor measures. Further research is needed to demonstrate a causal relationship between vitamin D and cognitive function and determine if cognition plays a role in falls reduction.
Objective— Adverse cardiovascular events occur more frequently in the morning than at other times of the day. Vascular endothelial function (VEF)—a robust cardiovascular risk marker—is impaired during this morning period. We recently discovered that this morning impairment in VEF is not caused by either overnight sleep or the inactivity that accompanies sleep. We determined whether the endogenous circadian system is responsible for this morning impairment in VEF. We also assessed whether the circadian system affects mechanistic biomarkers, that is, oxidative stress (malondialdehyde adducts), endothelin-1, blood pressure, and heart rate. Approach and Results— Twenty-one (11 women) middle-aged healthy participants completed a 5-day laboratory protocol in dim light where all behaviors, including sleep and activity, and all physiological measurements were evenly distributed across the 24-hour period. After baseline testing, participants underwent 10 recurring 5-hour 20-minute behavioral cycles of 2-hour 40-minute sleep opportunities and 2 hours and 40 minutes of standardized waking episodes. VEF, blood pressure, and heart rate were measured, and venous blood was sampled immediately after awakening during each wake episode. Independent of behaviors, VEF was significantly attenuated during the subjective night and across the morning ( P =0.04). Malondialdehyde adducts and endothelin-1 exhibited circadian rhythms with increases across the morning vulnerable period and peaks around noon ( P ≤0.01). Both systolic ( P =0.005) and diastolic blood pressure ( P =0.04) were rhythmic with peaks in the late afternoon. Conclusions— The endogenous circadian system impairs VEF and increases malondialdehyde adducts and endothelin-1 in the morning vulnerable hours and may increase the risk of morning adverse cardiovascular events in susceptible individuals. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT02202811.
The data indicate that PTSD in the chronic and unprovoked state is not characterized by an acute biological stress response.
Background. Sleep and melatonin have been associated with healthy aging. In this study, we examine the association between melatonin levels and sleep among older men. Methods. Cross-sectional study of a community-dwelling cohort of 2,821 men aged 65 years or older recruited from six U.S. centers. First morning void urine samples were collected to measure melatonin's major urinary metabolite, 6-sulfatoxymelatonin (aMT6s). We also assessed objective and subjective sleep parameters. We used logistic regression models to calculate multivariate (MV) odds ratios (ORs), and 95% confidence intervals (CIs) adjusted for important demographic variables and comorbidities. Results. In the overall sample, the only significant finding in fully adjusted models was that aMT6s levels were inversely associated with subjectively measured daytime sleepiness (sleepiness mean score of 5.79 in the top aMT6s quartile, and 6.26 in the bottom aMT6s quartile, MV OR, 1.32; 95% CI, 0.95-1.84; p trend ≤ .02). When restricting to men without β-blocker use (a known melatonin suppressant), aMT6s levels were significantly associated with shorter sleep time, that is, less than 5 hours (MV OR, = 1.90; 95% CI, 1.21-2.99; p trend = .01), and worse sleep efficiency, that is, less than
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