View clinical trials related to Cerebrovascular Function.
Filter by:Oral supplements containing exogenous ketones have recently become available and represent a novel tool for increasing plasma ketone bodies without the need for dietary restriction. Early evidence suggests that oral ketone supplements may enhance cerebral blood flow (CBF). However, a higher dose of a ketone monoester has been shown to slightly lower blood pH and reduce end-tidal CO2 (PetCO2) due to compensatory hyperventilation, which is accompanied by parallel reductions in CBF. Whether reductions in PetCO2 causes reductions in CBF is currently unknown. The purpose of this study is to investigate the effect of manipulating PetCO2 at normocapnia (PetCO2 maintained at baseline) or poikilocapnia (no PetCO2 targeting; breathing room air), following the ingestion of a dose of a ketone monoester on CBF and cerebrovascular reactivity to CO2 in young adults.
Ketone bodies are produced by the liver during periods of food scarcity or severe carbohydrate restriction. Blood ketones are an alternative fuel source used by the brain, heart, and skeletal muscle during periods of fasting. Further, ketones bodies act as a signalling molecule that have pleiotropic effects that upregulate cellular stress-resistance pathways throughout the body. Oral supplements containing exogenous ketones have recently become available and represent a novel tool for increasing plasma ketone bodies without the need for dietary restriction. Early evidence suggests that oral ketone supplements may enhance cerebral blood flow and improve cognition. However, the dose-dependent effects of a single ketone supplement on cerebral blood flow and cognition in young adults is currently unknown. The purpose of this study is to characterize the effects of ingesting a high versus low dose of an oral ketone monoester on cerebral blood flow, circulating blood markers, and cognition in young adults. As an exploratory aim, this study will investigate how oxygen uptake kinetics during submaximal exercise are impacted 2 hours after ingestion of a ketone supplement. Recent findings indicate that ketone supplementation may impair exercise performance due to the physiological stress (i.e., pH disturbances) imposed by an acute ketone dose. Delaying exercise onset by 2 hours after ingestion of a ketone supplement may enhance oxygen kinetics in a dose-dependent manner.
People who report subjective memory complaints have a greater risk of developing dementia. Memory issues may be an early warning sign of dysfunctional cerebral glucose metabolism and cerebral blood flow. Interventions that can restore cerebral metabolism and enhance cerebral blood flow may protect against conversion to dementia. Exogenous ketone supplements have been shown rapidly improves brain network function in young adults. Further, infusion studies demonstrate that ketone bodies enhance cerebral blood flow in cognitively normal adults. Whether acute ketone monoester supplementation can improve brain function in adults with subjective memory complaints is currently unknown. This study will investigate the effects of a single ketone monoester dose on resting-state functional connectivity in the default mode network and resting cerebral blood flow in adults with subjective memory complaints.
Aging tends to compromise the ability to solve problems, remember details, and process information. At the extreme level, this normal cognitive decline can interfere with independent living. Because most brain dysfunctions become irreversible before patients show clear signs in the clinic, there is a pressing need to prioritize preventative countermeasures. Exercise is a promising strategy to slow or reverse these losses. While most studies have looked at running or cycling exercise, little is known about the effects of weight lifting exercise. In addition, vascular health is intimately linked with cognitive abilities and risk of stroke, making it a primary target for intervention. Previous weight lifting studies suggest that blood vessels in the brain are a likely site of adaptation. The goal of this research is to understand how weight lifting exercise improves cognitive function in older adults. Specifically, the contribution of blood vessel changes in the brain after 12 weeks of weight lifting exercise 3 days per week. These vascular improvements may provide the link between physical and cognitive health, while simultaneously reducing the risk of cardiovascular disease and stroke. To determine this, advanced brain imaging techniques will be used to measure blood flow/volume changes in the brain non-invasively. Physical capacity (i.e. strength), body composition (i.e. lean mass, fat mass), and blood markers will also be assessed using standard protocols, and each of these variables will be tested for their relationship with cognitive functions. Understanding how weight lifting exercise improves cognitive function will support the development of comprehensive treatments targeting overall brain health. With no current cures for dementia, this information will be vital in prescribing exercise for specific patient needs to reducing the risk of dementia and stroke. In addition, the promise of exercise therapies extends beyond the target disease, having further benefits to the well-being of participants. These types of treatments positively impact fundamental aging processes, and thus reduce the risk of all-cause mortality. Even with moderate benefits to a specific disease like dementia, the global impact on healthcare would be substantial.
Cognitive performance is negatively related to an impaired glucose metabolism, possibly due to impairments in brain vascular function. Supported by the statement from the American Heart and Stroke Association that physical exercise is one of the most effective strategies to protect against cognitive decline, we now hypothesize that exercise-induced changes in glucose metabolism cause beneficial effects on brain vascular function thereby improving cognitive performance. The primary objective of this intervention study is thus to evaluate in sedentary elderly men the effect of a 8-week aerobic-based exercise program on cerebral blood flow, as quantified by the non-invasive gold standard magnetic resonance imaging (MRI) perfusion method Arterial Spin Labeling (ASL). Cerebral blood flow is a robust and sensitive physiological marker of brain vascular function. Secondary objectives are to examine effects on glucose metabolism using the oral glucose tolerance test and cognitive performance as assessed with a neurophysiological test battery.