The word ‘dementia’ is used to describe the symptoms people experience when their brain cells stop working properly due to a disease. This can be experiencing memory problems, such as frequently losing things, or struggling to find the right words in conversation. When people hear the word dementia, many think of those they know with memory and thinking problems caused by Alzheimer’s disease. Although Alzheimer’s is the leading cause of dementia, vascular dementia affects 150,000 people in the UK, accounting for one in five of all dementia cases.
Vascular dementia does not have a single cause, and it’s not even a single disease. It is caused by a number of different conditions that all relate to problems with the supply of blood to the brain.
Without enough blood supply, cells in the brain do not receive enough oxygen and so they become damaged and die. The symptoms of this damage include slower thinking and personality changes, as well as some movement problems and issues with stability.
The blood supply to our brains can be disrupted in different ways and so vascular dementia is often described as having different subtypes.
What does stroke have to do with dementia?
Most vascular dementia cases, roughly 30%, are caused by stroke. When someone has a stroke, the blood flow to the brain is disrupted and this damages brain cells.
This disruption can happen as a result of a blood vessel bursting, which is a haemorrhagic stroke, or due to a clot blocking a vessel, which is an ischaemic stroke. Ischaemic strokes are the most common and are usually linked to vascular dementia.
Ischaemic strokes can cause single or multi-infarct dementia. The term infarct refers to an area of dead tissue as a result of a lack of blood supply. Single-infarct dementia occurs when there a is large area of damage in one part of the brain.
Multi-infarct dementia occurs after a series of strokes in different parts of the brain. If many areas of the brain are affected in this way, the person will experience a range of symptoms relating to the region that is damaged. For example, speech and movement may be affected over time as different strokes occur in different brain regions.
Damage to brain tissue
Another major cause of vascular dementia occurs when the damaged cells are found in an area of the brain called white matter – this is sometimes referred to as subcortical vascular dementia.
The brain is made up of white and grey matter, relating to the colour of your brain’s tissue. Grey matter is found around the outer edge of the brain and contains the parts of brain cells that communicate with each other, the synapses. The white matter is deeper inside the brain and contains the parts of brain cells that carry messages from one area of the brain to another, allowing us to do everything we usually do like eat, move and talk.
If the white matter does not receive blood supply, these cells die and so the connections across the brain become lost, causing the typical symptoms of dementia.
In dementia the damage to cells in the white matter is often related to small vessel disease, where the small blood vessels become narrow and blood cannot flow through. This happens naturally as we age, but conditions like high blood pressure or behaviours like smoking can make this worse.
There are also a number of other diseases that can cause damage in the white matter, and therefore cause vascular dementia, for example:
- Lacunar lesions are a type of stroke that happen in the very small arteries deep within the white matter of the brain.
- Binswanger disease is characterised by the narrowing of arteries reducing blood flow and leading to cell death.
Can I have two different types of dementia?
Yes, you can. This is called mixed dementia and occurs when someone has more than one type of dementia. In many cases this might be Alzheimer’s disease and vascular dementia.
Thanks to incredible supporters like you, we’re currently funding a range of projects that are investigating the mechanisms in the brain that cause Alzheimer’s disease and vascular dementia to occur alongside each other. So far, these projects have shown that a reduction in blood flow in the brain can lead to disease processes relating to both types of dementia.
A group in Edinburgh have found that specific immune cells in the brain, microglia, are affected by a reduction in blood flow, and then go on to affect learning and memory. Meanwhile a group in London have identified that many people with Alzheimer’s have blood vessel damage consistent with that seen in vascular dementia, as well as having a build-up of amyloid protein, which is a key hallmark of Alzheimer’s disease.
Despite many older people having both Alzheimer’s disease and vascular problems, relatively few are diagnosed with ‘mixed dementia’. Doctors can only diagnose mixed dementia where there are clear signs of both types of disease directly contributing to dementia symptoms.
What can I do to keep my brain healthy?
What makes up our risk of developing dementia is a complex mix of factors such as age, genetics and lifestyle factors. While we cannot change our age or genetic makeup, we can make positive lifestyle changes that will help to reduce our overall risk of developing dementia, and that is worthwhile.
Steps to look after our heart health can help reduce our risk of dementia, especially vascular dementia and Alzheimer’s disease. This includes lifestyle approaches such as: stopping smoking, being physically active every day, eating a balanced diet, maintaining a healthy weight, drinking alcohol in line with government recommendations, and keeping mentally active.
If you are worried that you are experiencing any signs or symptoms of dementia, it is best to discuss these with your doctor.
If have any questions about dementia, or want to take part in research, you can contact the Dementia Research Infoline by phone on 0300 111 5 111 (9-5pm Monday to Friday) or by email at email@example.com.
Watch Olive’s story to hear from someone living with vascular dementia: