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Addressing the knowledge gaps in two common age-related conditions, both associated with nutrition and physical activity: Alzheimer’s Dementia and Sarcopenia
- Author / Creator
- Juby, Angela G
There is an aging demographic in many countries resulting in an increased prevalence of age-associated chronic disease, particularly Alzheimer's dementia [AD] and sarcopenia. Both conditions significantly impact independence. They also have other common effects on morbidity: Both conditions also have no single diagnostic test, and require fulfillment of clinical diagnostic criteria. Diagnosis of AD relies on history, physical, and investigations to exclude other diagnoses. Diagnosis of sarcopenia requires muscle strength, mass, and function assessments. Tools to help in the diagnosis of AD are readily available (clinical cognitive tests), whereas tools to diagnose sarcopenia, particularly muscle mass assessment, require sophisticated diagnostics that are not readily available. However, unlike AD, treatment for sarcopenia has been well studied and validated. In AD despite extensive research, to date, there are limited therapeutic options, so the treatment becomes one of following the decline and planning for future disability.
These projects were undertaken to address some of the clinical care gaps in these two highly prevalent, interrelated, impactful, clinical conditions.
In AD, traditional approaches to therapy attempting to reduce amyloid load have proven ineffective.
The first study (Chapter 3) evaluates the use of medium chain triglyceride (MCT) supplementation as a source of dietary ketones for brain energy. It looks at the ketogenic effect (β-hydroxybutyrate (BHB) levels) of multiple doses of MCT in participants with and without AD.
The second study (Chapter 4) evaluates the cognitive effect and safety of MCT versus olive oil supplementation in participants with established AD, in a randomised, double-blind, placebo-controlled, cross-over trial with an open label extension (15-month trial). Cognition is measured with standardised tools-Mini-Mental Status Examination, Montreal Cognitive Assessment, and Cognigram®.
The third study (Chapter 5) evaluates office-based, direct-to-consumer, bioimpedance scales as a means to easy clinical assessment of muscle and fat mass, and compares this to dual energy Xray absorptiometry (DXA) as the gold standard, in a group of community-dwelling older adults.
The fourth study (Chapter 6) evaluates the rate of sarcopenia in a cohort of independent, community-dwelling older adults, and the change in their sarcopenic status over 12-months. It also assesses involvement in a social group activity program on quality of life, and physical function.
Study 1 showed that MCT is an equally effective nutritional source of ketones (beta-hydroxybutyrate, BHB) in participants with and without AD. Study 2 showed no difference between MCT and placebo oil in the cross-over phase. Including the open-label phase showed exposure to a total of 11-months of continuous supplemental MCT, of at least 30ml daily, provided cognitive benefit (stability or decreased decline) in participants with established AD, compared to those in whom the 11-months was interrupted by 4 months of placebo (olive) oil. Participants with a higher baseline cognitive score showed greater benefits. In Study 3, office-based direct-to-consumer bioimpedance scales were shown to be correlated with dual-energy Xray absorptiometry (DXA) for percentage muscle mass and fat measurements. Study 4 showed that the rate of sarcopenia was slightly higher than anticipated (7.1%), but similar to the UK. The high rate of pre-sarcopenia (28.6%) was unexpected. The prevalence of obesity was highly variable depending on DXA and BIA body composition versus BMI criteria. Sarcopenic status did not appear to be correlated with cognitive scores, but was associated with activities of daily living function and quality of life, as reported in the literature. There was maintenance of function in the majority of participants over 12-months. The group social activity program (including both aerobic, resistance and balance exercises), despite its non-progressive, non-personalised nature, was shown to improve the balance component of the Tinetti score. Self-reported leisure activity was not found to be associated with sarcopenic status or Tinetti scores.
AD and sarcopenia are more prevalent with increasing age. These studies show that the MCT induced BHB response is unaffected by age or AD status, and that 11-months continuous consumption of MCT, may influence the AD disease course in participants with established AD. Community-based, direct-to-consumer BIA scales can improve office-based diagnostic ability for muscle mass and obesity. The rate of sarcopenia in independent community-dwelling older adults was higher than predicted, but remained relatively stable over 12-months.
- Graduation date
- Fall 2022
- Type of Item
- Doctor of Philosophy
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