Video: Small arteries, Big Consequences at Brain Health Day 2023
Listen to Dr Harry Pritchard, a Research Fellow in the Division of Cardiovascular Sciences, describe the impact of a reduced blood flow to the brain in dementia. He describes work currently ongoing at Manchester to study how blood vessels, smaller than a width of hair, can become damaged and potentially lead to dementia onset.
What is dementia?
- Dementia is a group of progressive disorders which overtime cause the cells in the brain (neurons) to stop functioning correctly.
- The most common type of dementia is Alzheimer’s disease, followed by vascular dementia.
- Symptoms can vary depending on the region of the brain affected. These include problems with memory, communication, decision-making and behavioural changes.
- It is the leading cause of death in the UK, with cases expected to rise to over 1,000,000 by 2025.
What are the small vessels in our brain?
- Our brains have a very extensive network of blood vessels, carrying blood containing oxygen and nutrients.
- Blood enters the surface of the brain through the pial arteries and then flows into smaller arteries (penetrating arterioles). These supply blood to the brain’s capillaries, which provide neurons with the oxygen and nutrients they need to survive.
- The arteries in the brain contain smooth muscle cells that are able to contract (reduce blood flow) and relax (increase blood flow). This ensures the brain always has a constant supply of blood (autoregulation) and that more active areas of the brain are receiving more blood flow.
Why are they important in dementia?
- Many risk factors for dementia, such as high blood pressure (hypertension), obesity, diabetes, all affect how well our blood vessels function.
- In cases of Alzheimer’s disease and vascular dementia, it has been shown there is reduced blood flow through cerebral blood vessels, meaning less blood is entering the brain.
- In many cases of dementia, this can be seen before diagnosis and may indicate development of more severe disease.
What are scientists trying to do?
- Currently, scientists are trying to understand what causes the cerebral vessels to stop functioning correctly in dementia. Once we understand how blood flow is reduced, we may be able to develop new treatments to restore blood flow.
- To study this in the laboratory, scientists use animal models of dementia. Their arteries are removed and placed in a solution similar to the blood.
- As the arteries are extremely small (more than 4 times smaller than a human hair!) specialist techniques have been developed to study how their activity changes under different conditions.
- In Manchester, one study in Alzheimer’s disease has shown that specific ion channels, controlling contraction of the smooth muscle cells around the cerebral arteries, may not be working correctly. This means that cerebral arteries were contracting more, leading to less blood flow to the brain.