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Vascular dementia is the second most common type of dementia (after Alzheimer’s disease).
The word ‘dementia’ describes a set of symptoms that can include memory loss and difficulties with thinking, problem-solving or language. In vascular dementia, these symptoms occur when certain parts of the brain are damaged because of problems with blood supply.
Vascular dementia is caused by reduced blood supply to certain parts of the brain due to diseased blood vessels.
To stay healthy and function properly, brain cells need a constant supply of oxygen and nutrients. These are present in the blood, and are pumped to the brain through a network of vessels called the ‘vascular system’. If blood vessels in the brain’s vascular system are damaged by disease, they can gradually become blocked, stiff and twisted, or they can leak. This means they are not able to supply enough blood to keep the cells around them healthy. Eventually, these brain cells become so starved of oxygen and nutrients that they die.
Over time, as more brain cells die and are not replaced, problems begin to occur with memory, thinking or reasoning – together known as ‘cognition’. When cognitive problems caused by vascular disease begin to affect everyday tasks, the condition is known as ‘vascular dementia’.
Types of vascular dementia
There are several types of vascular dementia – explained below. The type of vascular dementia someone has is determined by the underlying cause and the area of the brain that is affected. The various types of vascular dementia have different symptoms. They also progress at different rates.
Subcortical vascular dementia
Subcortical vascular dementia is thought to be the most common type of vascular dementia. It is caused by diseases of the very small blood vessels that lie deep in the brain (this is called small vessel disease). Over time, these blood vessels can develop thick walls and become stiff and twisted, so blood cannot travel through them easily. The brain tissue supplied
by these blood vessels becomes starved of oxygen and nutrients, so eventually it dies and the cells are lost.
Vascular dementia caused by small vessel disease happens much more slowly and gradually than other types of vascular dementia. The damage happens in a region of the brain called the ‘subcortex’ which is very important for controlling movement and emotions. This means that these aspects of thinking are particularly affected.
Vascular dementia can be caused by a stroke, which happens when the blood supply to a part of the brain is suddenly cut off. In most strokes, a blood vessel in the brain becomes narrowed and is blocked by a clot. The clot may have formed in the brain or, if someone has heart disease, it may have formed in the heart and been carried to the brain. Some strokes
are more severe than others, depending on where the blocked vessel is and for how long the blood supply is interrupted (this can be permanent or temporary).
Dementia after a major stroke (‘post-stroke dementia’)
A major stroke occurs when the blood flow in a large vessel in the brain is suddenly and permanently cut off. This usually happens when the vessel is blocked by a clot. Sometimes, it is because the vessel bursts and bleeds into the brain, but this is much less common. About one person in every five who have had a major stroke goes on to develop vascular dementia within six months.
Someone who has already had a major stroke is also at greater risk of having another one. This is because the health problems that led to their original stroke (such as high blood pressure or heart problems) can cause another clot to happen. The more strokes that someone has, the more of their brain function they will lose overall. This means that they are more likely to develop dementia.
Single-infarct and multi-infarct dementia
Single or multi-infarct dementia is caused by one or more smaller strokes. These strokes happen when a large or medium-sized blood vessel is blocked by a clot. The stroke may be so small that there are no noticeable symptoms. Sometimes the blockage in the blood vessel can clear itself. This means that the symptoms of the stroke (such as weakness down one side of the body, or slurred speech) may only be temporary – lasting perhaps a few minutes. If symptoms last for less than 24 hours this is known as a ‘mini-stroke’ or ‘transient ischaemic attack’ (TIA).
A TIA may sometimes be dismissed mistakenly as a ‘funny turn’.
If the blood supply is interrupted for more than a few minutes, the stroke will lead to the death of a small area of tissue in the brain. This area is known as an ‘infarct’. Sometimes just one infarct forms in an important part of the brain and this causes dementia (known as single-infarct dementia). Much more often, a series of small strokes over a period of weeks or months lead to a number of infarcts spread around the brain. Dementia in these cases is caused by the total damage of all the infarcts combined. This is known as ‘multi-infarct dementia’.
The way someone is affected by vascular dementia varies. The symptoms will depend on the underlying causes of the vascular dementia, the areas of the brain which are affected and just because everybody is different. Symptoms may develop suddenly (for example, after a stroke) or more gradually (such as with small vessel disease).
Some of the symptoms of vascular dementia can be similar to those of other types of dementia, particularly memory problems, taking longer
to process thoughts and changes in behaviour. However, they may not appear in exactly the same ways as with other types of dementia. For example, memory loss is very common in the early stages of Alzheimer’s disease, but is not usually the main early symptom of vascular dementia.
The most common cognitive symptoms during the early stages of vascular dementia are:
Problems with planning or organising, making decisions or solving problems difficulties following a series of steps (such as when cooking a meal) slower speed of thought
Problems concentrating, including short periods of sudden confusion.
A person in the early stages of vascular dementia may also have difficulties with:
their memory – they may have problems recalling recent events (although this may be mild)
their language – for example their speech may become less fluent.
As well as these cognitive symptoms, it is common for someone with early vascular dementia to experience mood changes such as apathy, depression or anxiety. Depression is a particularly common symptom, partly because someone may be aware of the difficulties their condition is causing. A person with vascular dementia may also become generally more emotional. They may be prone to mood swings and being unusually tearful or happy.
Other symptoms vary between the different types of vascular dementia. Symptoms for post-stroke vascular dementia can depend on which part of the brain has been affected. If a certain part of the brain is affected someone might have paralysis or weakness of a limb. If a different part of the brain is damaged they may have problems with vision or speech. With rehabilitation, symptoms can get a little better or stabilise for a time, especially in the first six months after the stroke.
The symptoms for subcortical vascular dementia are typically more consistent than other types of vascular dementia. Early loss of bladder control is common, which causes problems with continence. As the damage to the brain occurs in the subcortex, movement and emotion can be particularly affected.
This means that someone with subcortical vascular dementia may also have mild weakness on one side of their
body, or become less steady when walking and more prone to falls. Other symptoms may include clumsiness, lack of facial expression and problems pronouncing words.
Progression and later stages
Vascular dementia is ‘progressive’, which means that it will continue to
get worse with time. However, the speed and pattern of this progression can vary greatly. For example, stroke-related dementia often progresses
in a ‘stepped’ way, with long periods when symptoms are stable and
then periods when symptoms rapidly get worse. This is because each additional stroke causes further damage to the brain. Subcortical vascular dementia can occasionally follow this stepped progression. More often, however, symptoms get worse gradually as the area of affected tissue slowly expands.
Over time, a person with vascular dementia is likely to develop more severe confusion or disorientation, and further problems with reasoning and communication. Memory loss will also become worse, for example with recent events or names. They are also likely to need more support with day-to-day activities such as cooking or cleaning.
As vascular dementia progresses, many people also develop behaviours that seem unusual or out of character. They may become more irritable, agitated, aggressive or have a disturbed sleep pattern. Someone may also act in ways which could be considered rude or inappropriate. This is often because they have an unmet need which they are trying to communicate. For example they may be hungry, thirsty or under-stimulated.
Someone experiencing the later stages of vascular dementia may become much less aware of what is happening around them. They may have difficulties walking or eating without help, and may become increasingly frail. Eventually, they will need help with all their daily activities.
It is very difficult to predict how long somebody with vascular dementia will live. This is because everybody’s experience of dementia is different. However, someone with vascular dementia will probably not live as long as they would do if they didn’t have the condition. This is largely because someone with vascular dementia is more likely to have other serious health conditions such as heart disease or high blood pressure. The severity of these other health conditions is a large factor in how long somebody will live. Generally they are more likely to die from having a stroke or heart attack related to these health conditions than from the dementia itself.
Please see this factsheet for ore information: