A methodology for an acute exercise clinical trial called dementia risk and dynamic response to exercise

Biomarker Responses to Acute Exercise and Relationship with Brain Blood Flow

BACKGROUND

There is evidence that aerobic exercise is beneficial for brain health, but these effects are variable between individuals and the underlying mechanisms that modulate these benefits remain unclear.

OBJECTIVE

We sought to characterize the acute physiological response of bioenergetic and neurotrophic blood biomarkers to exercise in cognitively healthy older adults, as well as relationships with brain blood flow.

METHODS

We measured exercise-induced changes in lactate, which has been linked to brain blood flow, as well brain-derived neurotrophic factor (BDNF), a neurotrophin related to brain health. We further quantified changes in brain blood flow using arterial spin labeling.

RESULTS

As expected, lactate and BDNF both changed with time post exercise. Intriguingly, there was a negative relationship between lactate response (area under the curve) and brain blood flow measured acutely following exercise. Finally, the BDNF response tracked strongly with change in platelet activation, providing evidence that platelet activation is an important mechanism for trophic-related exercise responses.

CONCLUSIONS

Lactate and BDNF respond acutely to exercise, and the lactate response tracks with changes in brain blood flow. Further investigation into how these factors relate to brain health-related outcomes in exercise trials is warranted.

Comparative efficacy of various exercise interventions on depression in older adults with mild cognitive impairment: A systematic review and network meta-analysis

BACKGROUND

Exercise is a promising nonpharmacological treatment for improving depression in older adults with MCI, but it is unclear which exercises are most effective. The objectives of this study were to compare and rank the effectiveness of various exercise interventions for depression in mild cognitive impairment (MCI) and to investigate the effects of exercise on depression.

METHODS

The PRISMA-NMA guidelines were applied to the development and reporting of review criteria. The Cochrane Library, Web of Science, PsycINFO, PubMed, EMBASE, CINAHL, and Scopus databases were systematically searched by combining search terms for randomized controlled trial studies (RCTs) published in English from individual databases with the earliest available date set to March 10, 2023. Two evaluators independently selected and evaluated eligible studies of changes in depression in older adults with MCI after an exercise intervention. A protocol for this systematic review was registered in PROSPERO (Registration number: CRD42022377052).

RESULTS

A network meta-analysis was conducted on 15 eligible RCTs consisting of 4271 subjects, including aerobic (n = 6), mind-body (n = 6) and multicomponent (n = 3) exercise trials. Compared to controls, mind-body exercise showed the strongest improvement in depressive symptoms (SMD = -0.63, 95% CI: -1.13, -0.14), followed by aerobic (SMD = -0.57, 95% CI: -0.88, -0.26) and multicomponent exercise (SMD = -0.53, 95% CI: -1.02, -0.03). Notably, there were no statistically significant differences between exercise types: aerobic vs. mind-body (SMD = 0.06, 95% PrI: -0.71, 0.84), multicomponent vs. mind-body (SMD = 0.11, 95% PrI: -0.75, 0.97), or multicomponent vs. aerobic (SMD = 0.04, 95% PrI: -0.771, 0.86).

CONCLUSIONS

In this review, we found that mind-body exercise was most effective when compared to conventional controls and that multiple exercise modalities (aerobic, mind-body, and multicomponent exercise) had beneficial and comparable effects in reducing depressive states in older adults with MCI. These findings may guide clinical geriatric stakeholders and allied health professionals in providing more scientifically optimal exercise prescriptions for older adults with MCI. In the future, more high-quality, long-term clinical trials are needed to support the exploration of longer-term dynamic effects.

Hippocampal blood flow rapidly and preferentially increases after a bout of moderate-intensity exercise in older adults with poor cerebrovascular health

Over the course of aging, there is an early degradation of cerebrovascular health, which may be attenuated with aerobic exercise training. Yet, the acute cerebrovascular response to a single bout of exercise remains elusive, particularly within key brain regions most affected by age-related disease processes. We investigated the acute global and region-specific cerebral blood flow (CBF) response to 15 minutes of moderate-intensity aerobic exercise in older adults (≥65 years; n = 60) using arterial spin labeling magnetic resonance imaging. Within 0-6 min post-exercise, CBF decreased across all regions, an effect that was attenuated in the hippocampus. The exercise-induced CBF drop was followed by a rebound effect over the 24-minute postexercise assessment period, an effect that was most robust in the hippocampus. Individuals with low baseline perfusion demonstrated the greatest hippocampal-specific CBF effect post-exercise, showing no immediate drop and a rapid increase in CBF that exceeded baseline levels within 6-12 minutes postexercise. Gains in domain-specific cognitive performance postexercise were not associated with changes in regional CBF, suggesting dissociable effects of exercise on acute neural and vascular plasticity. Together, the present findings support a precision-medicine framework for the use of exercise to target brain health that carefully considers age-related changes in the cerebrovascular system.

Proceedings from the Albert Charitable Trust Inaugural Workshop on 'Understanding the Acute Effects of Exercise on the Brain'

An inaugural workshop supported by "The Leo and Anne Albert Charitable Trust," was held October 4-7, 2019 in Scottsdale, Arizona, to focus on the effects of exercise on the brain and to discuss how physical activity may prevent or delay the onset of aging-related neurodegenerative conditions. The Scientific Program Committee (led by Dr. Jeff Burns) assembled translational, clinical, and basic scientists who research various aspects of the effects of exercise on the body and brain, with the overall goal of gaining a better understanding as to how to delay or prevent neurodegenerative diseases. In particular, research topics included the links between cardiorespiratory fitness, the cerebrovasculature, energy metabolism, peripheral organs, and cognitive function, which are all highly relevant to understanding the effects of acute and chronic exercise on the brain. The Albert Trust workshop participants addressed these and related topics, as well as how other lifestyle interventions, such as diet, affect age-related cognitive decline associated with Alzheimer's and other neurodegenerative diseases. This report provides a synopsis of the presentations and discussions by the participants, and a delineation of the next steps towards advancing our understanding of the effects of exercise on the aging brain.

Dementia risk and dynamic response to exercise: A non-randomized clinical trial

Background

Physical exercise may support brain health and cognition over the course of typical aging. The goal of this nonrandomized clinical trial was to examine the effect of an acute bout of aerobic exercise on brain blood flow and blood neurotrophic factors associated with exercise response and brain function in older adults with and without possession of the Apolipoprotein epsilon 4 (APOE4) allele, a genetic risk factor for developing Alzheimer’s. We hypothesized that older adult APOE4 carriers would have lower cerebral blood flow regulation and would demonstrate blunted neurotrophic response to exercise compared to noncarriers.

Methods

Sixty-two older adults (73±5 years old, 41 female [67%]) consented to this prospectively enrolling clinical trial, utilizing a single arm, single visit, experimental design, with post-hoc assessment of difference in outcomes based on APOE4 carriership. All participants completed a single 15-minute bout of moderate-intensity aerobic exercise. The primary outcome measure was change in cortical gray matter cerebral blood flow in cortical gray matter measured by magnetic resonance imaging (MRI) arterial spin labeling (ASL), defined as the total perfusion (area under the curve, AUC) following exercise. Secondary outcomes were changes in blood neurotrophin concentrations of insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), and brain derived neurotrophic factor (BDNF).

Results

Genotyping failed in one individual (n = 23 APOE4 carriers and n = 38 APOE4 non-carriers) and two participants could not complete primary outcome testing. Cerebral blood flow AUC increased immediately following exercise, regardless of APOE4 carrier status. In an exploratory regional analyses, we found that cerebral blood flow increased in hippocampal brain regions, while showing no change in cerebellum across both groups. Among high inter-individual variability, there were no significant changes in any of the 3 neurotrophic factors for either group immediately following exercise.

Conclusions

Our findings show that both APOE4 carriers and non-carriers show similar effects of exercise-induced increases in cerebral blood flow and neurotrophic response to acute aerobic exercise. Our results provide further evidence that acute exercise-induced increases in cerebral blood flow may be regional specific, and that exercise-induced neurotrophin release may show a differential effect in the aging cardiovascular system. Results from this study provide an initial characterization of the acute brain blood flow and neurotrophin responses to a bout of exercise in older adults with and without this known risk allele for cardiovascular disease and Alzheimer’s disease.

Trial registration

Dementia Risk and Dynamic Response to Exercise (DYNAMIC); Identifier: NCT04009629.

Types of exercise and training duration on depressive symptoms among older adults in long-term care facilities

BACKGROUND

Depression is associated with a greater risk of disability, cognitive impairment, and suicide. Older adults in long-term care facilities (LTCFs) are more likely to develop depression due to changes in family roles and separation from family members. The aim of this study was to synthesize and analyze the effects of different types of exercise and training duration on depressive symptoms of older adults in LTCFs.

METHODS

Relevant peer-reviewed journal articles published in English were identified through a search of six electronic databases up to June 2021.

RESULTS

A total of 25 studies were included in the systematic review and 22 in the meta-analysis. The results of meta-analysis showed that exercise interventions reduced depression in cognitively intact older adults and in cognitively impaired older adults. Both exercising less than 150 min per week or more than 150 min per week, reduced depressive symptoms of older adults. In terms of exercise types, mind-body exercises, exergames, and strength training reduced depressive symptoms.

CONCLUSION

Exercise has a positive effect on reducing depressive symptoms with mind-body exercises, exergames, and strength training producing the best effect. Regardless of cognitive impairment, older adults in LTCFs benefited from exercise in reducing depressive symptoms.