Experimental gerontology
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Experimental gerontology · Jul 2018
Comparative StudyA cross-sectional comparison of brain glucose and ketone metabolism in cognitively healthy older adults, mild cognitive impairment and early Alzheimer's disease.
Deteriorating brain glucose metabolism precedes the clinical onset of Alzheimer's disease (AD) and appears to contribute to its etiology. Ketone bodies, mainly β-hydroxybutyrate and acetoacetate, are the primary alternative brain fuel to glucose. Some reports suggest that brain ketone metabolism is unchanged in AD but, to our knowledge, no such data are available for MCI. ⋯ This quantitative kinetic PET and MRI imaging protocol for brain glucose and acetoacetate metabolism confirms that the brain undergoes structural atrophy and lower brain energy metabolism in MCI and AD and demonstrates that the deterioration in brain energy metabolism is specific to glucose. These results suggest that a ketogenic intervention to increase energy availability for the brain is warranted in an attempt to delay further cognitive decline by compensating for the brain glucose deficit in MCI and AD.
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Experimental gerontology · Jun 2018
Genetically elevated gamma-glutamyltransferase and Alzheimer's disease.
Observational epidemiological evidence supports a linear and independent association between serum gamma-glutamyltransferase (GGT) concentrations and the risk of Alzheimer's disease (AD). However, the causality of this association has not been previously investigated. We sought to assess the causal nature of this association using a Mendelian randomization (MR) approach. ⋯ The results were similar in both MR-Egger and weighted median MR methods. Overall, our findings cannot confirm a strong causal effect of GGT on AD risk. Further MR investigations using individual-level data are warranted to confirm or rule out causality.
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Experimental gerontology · Apr 2018
Multicenter StudyThe physical capabilities underlying timed "Up and Go" test are time-dependent in community-dwelling older women.
Timed 'Up and Go' (TUG) has been widely used in research and clinical practice to evaluate physical function and mobility in older adults. However, the physical capabilities underlying TUG performance are not well elucidated. Therefore, the present study aimed at investigating a selection of physical capacities underlying TUG performance in community-dwelling older women. ⋯ Multiple linear regression results indicate that the variability in TUG (~20%) was explained by lower limb muscle strength (13%) and power (1%), balance (4%), mobility (2%), and aerobic capacity (<1%), even after adjusted by age and age plus body mass index (BMI). However, when TUG results were added as quartiles, a decrease in the impact of physical capacities on TUG performance was determined. As a whole, our findings indicate that the contribution of physical capabilities to TUG performance is altered according to the time taken to perform the test, so that older women in the lower quartiles - indicating a higher performance - have an important contribution of lower limb muscle strength, while volunteers in the highest quartile demonstrate a decreased dependence on lower limb muscle strength and an increased contribution of other physical capabilities, such as lower limb muscle power and balance.
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Experimental gerontology · Oct 2017
The subsequent course of disability in older persons discharged to a skilled nursing facility after an acute hospitalization.
To evaluate the association between the type of acute hospitalization and subsequent course of disability in older persons discharged to a skilled nursing facility (SNF). ⋯ Among older persons discharged to a SNF after an acute hospitalization, the functional course over 6months was generally poor, with recovery to pre-hospital function observed in only one out of every four cases. Relative to elective major surgery, functional outcomes were worse for non-elective major surgery, critical illness, and other hospitalizations.
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Experimental gerontology · Oct 2017
Heat transfer and loss by whole-body hyperthermia during severe lower-body heating are impaired in healthy older men.
Most studies demonstrate that aging is associated with a weakened thermoregulation. However, it remains unclear whether heat transfer (for heat loss) from the lower (uncompensable) to the upper (compensable) body during passively-induced severe lower-body heating is delayed or attenuated with aging. Therefore, the main purpose of this study was to investigate heat transfer from uncompensable to compensable body areas in young men and healthy older men during passively-induced whole-body hyperthermia with a demonstrated post-heating change in core body (rectal; Tre) temperature. ⋯ However, the temperature increase in back skin and forearm skin (compensable areas) was significantly lower in older men than in young men (0.76±0.63 vs. 2.83±0.68°C; P<0.05 and 0.39±0.76 vs. 2.73±0.5°C; P<0.05, respectively). Furthermore, a post-warming increase in Tre of approximately 0.2°C was observed only in older men (P<0.05). In conclusion, older men whose lower extremities were immersed showed greater accumulation and storage of heat in the skin and deep muscles than young men, and this was associated with a greater heat-transfer delay and subsequent inertia in the increased core body (Tre) temperature.