New Peer-Reviewed Research Published in Frontiers of Neurology

New peer-reviewed research, using GlycoCheck, reveals the rest of the story about why blood flow and capillary density are so important to brain health.

 

The study, titled "Uncoupling of Microvascular Blood Flow and Capillary Density in Vascular Cognitive Impairment," was published in Frontiers in Neurology. The outcome of this study has led to GlycoCheck playing a role in The CRUCIAL Consortium, which brings together 12 partners from multiple fields (clinicians, fundamental scientists, scientific SMEs, exploitation and dissemination SME, management SME, and a patient advocacy), representing 7 different countries. Vascular dementia and heart failure represent major health burden to morbidity, mortality and quality of life.

 

Abstract of CRUCIAL Program:

 

Comorbidities (hypertension, aging, diabetes, etc.) affect all organs, but the brain and heart are especially sensitive to these chronic stresses resulting in cognitive impairment (a mental disorder) and heart failure (a non-mental disorder). These comorbidities also induce a reduction in microvascular density, called microvascular rarefaction. Diagnosis of microvascular rarefaction is limited by the inability to assess microvascular density. We have built a consortium, CRUCIAL, which will develop a coordinated program to establish clinical tools to measure rarefaction and investigate the role of microvascular rarefaction in cognitive impairment and heart failure.

 

Abstract for Uncoupling of Microvascular Blood Flow and Capillary Density in Vascular Cognitive Impairment:

 

Cerebral small vessel disease (cSVD) plays an important role in dementia and is a major cause for vascular cognitive impairment (VCI). Recent studies hypothesized that capillary dysfunction including reduction of capillary patency, rather than a flow-limiting pathology is crucial in cSVD. As cSVD is considered a systemic microvascular disease, we examined sublingual microvascular blood flow and capillary density in patients with VCI and controls. Fifteen patients with VCI due to cSVD and 15 controls underwent intravital microscopy of the sublingual microvessels. Microvascular blood flow and capillary density in high and low flow areas were determined for each participant. Flow-density coupling was examined by determining the ratio of density changes to flow changes, and the ratio of feed vessel red blood cell (RBC) velocity to capillary RBC velocity. These were compared between VCI and controls. In healthy controls, capillary density increased proportionally with feed vessel blood flow increase. In patients with VCI, no increase of capillary density was observed. Moreover, increase of feed vessel RBC velocity led to significant increase of capillary RBC velocity in VCI, whereas in controls, the capillary RBC increased only slightly. Flow-density coupling differed significantly between VCI and controls, also after correcting for age and hypertension. Our findings suggest uncoupling of microvascular blood flow and capillary density in patients with VCI. This uncoupling may impair oxygen and nutrients exchange when blood flow increases in response to increased metabolic demand, ultimately leading to tissue damage.

 

Summary for Our Readers Outside the Research and Medical Community

 

When the microvascular system is healthy and a person is in a resting state, some capillaries are without blood flow and go into reserve. That means that a low level of blood flow moves at a normal rate through only engaged capillaries. Notice in the illustration “Healthy Capillaries: Resting” (below left) that the feed flow equals 100, with the two engaged capillaries each at 50.

 

When the microvascular system is healthy and a person is in an active state of exercising or deep thinking, blood flow increases and capillaries in reserve are engaged. When capillaries in reserve are engaged, an increased level of blood flow moves at a normal rate through an increased number of perfused capillaries.

 

In the illustration “Healthy Capillaries: Active," below right, the feed flow equals 150, with the three engaged capillaries each at 50.

 

Key takeaway: The increased number of perfused capillaries when blood flow levels are elevated upon increased metabolic demand is vital so that a sufficient amount of nutrients can be delivered to active tissue cells of organs, along with an exchange of waste removed.