What is vascular dementia?

This sheet explains how vascular disease can lead to dementia, either suddenly following a stroke, or over time through a series of small strokes in the brain (multi-infarct dementia or MID). It outlines symptoms, causes and possible steps to reduce risks risks.

What is the effect of vascular disease in the brain?

The brain is the most complex organ in the body, needing plentiful amounts of oxygen to stay in good working order. Large blood vessels bring oxygen-bearing blood to the brain and a web of tiny blood vessels distribute it to every area.

Vascular disease describes a condition where the blood vessels are damaged and the supply of oxygen is at risk. If the oxygen supply fails in the brain, brain cells are likely to die, leading to strokes and possible vascular dementia. This disease is sometimes described as cerebral infarction. The effects may be:

• Strokes, which can be fatal but which may otherwise lead to physical disability and mental confusion or both.
• Multi-infarct dementia (MID), caused by a series of very small strokes in the brain
• A rare, slowly developing dementia caused by diseased blood vessels deep in the brain, known as subcortical vascular dementia or Binswanger's disease.

Stroke induced dementia

A full blown stroke occurs through a major obstruction or burst blood vessel in the brain. It causes severe damage and often leaves weakness or paralysis on one side of the body. It may also cause loss of balance and disturbed vision or speech. One person in five is left with mental damage or confusion following a stroke.

• The left side of the brain controls the right side of the body and is usually important for language. Stroke patients with right side paralysis are therefore more likely also to have language problems, calling things by a wrong name or using nonsense words. They may also have problems in understanding what is said to them, and answer yes or no to questions they have not understood, which can be confusing for carers.
• People with left side paralysis (i.e. damage to the right side of the brain) are more likely to have perception problems, finding it difficult to recognise people or things. Some are only aware of one side of their body, eating food only on one side of the plate, or brushing only one side of their hair.
• After a stroke a person's ability to switch their attention or to do two things at once may be damaged. They may stop walking, talking, or fail to follow a conversation when several people are speaking. They often feel tired and irritable and have a short attention span.

Multi-infarct dementia (MID)

Very small strokes in the brain may be experienced as 'dizzy spells' , but they can damage areas of the brain served by the very small arteries. Over a period of months or years the person may experience a number of attacks, each leaving them more confused and leading eventually to multi- infarct dementia, the most common cause of dementia after Alzheimer's disease.

• Symptoms can sometimes be distinguished from Alzheimer's - the mental decline is likely to have a clear start date, and symptoms tend to progress in a series of steps following each attack. Symptoms may include severe depression, mood swings and epilepsy.
• Some areas of the brain may be more affected than others and, as a result, some mental abilities may be relatively unaffected.
• The person is more likely to be aware of their mental decline than in Alzheimer's disease. This can increase depression.

Anyone who has had a stroke is at greater risk of another, and someone with MID is usually at high risk of further damage.

Diagnosis

The effects of one or more major strokes are usually sudden and clear-cut. Diagnosis of MID is more difficult. Family and friends may not detect any obvious events linked to mental deterioration, but see a progressive decline in mental powers. Sometimes, on reflection, they can recall illnesses which may have been minor strokes, or identify a more abrupt change. Scans may show infarct damage in the brain. However, it is not always possible to distinguish MID from Alzheimer's during life, and because both are common diseases in old age, it is possible for people to have both conditions. Click for more information about diagnosis

Can vascular dementia be prevented ?

Several factors increase the risk of vascular disease. The most significant are high blood pressure and smoking. Cigarette smoking is implicated in about a third of strokes.

• Stopping smoking, losing excess weight, taking exercise and reducing levels of salt in food are all ways to help prevent vascular disease and therefore strokes or MID.
• People at high risk of strokes, including those who have had a mild warning stroke (a transient ischaemic attack), can reduce the risks through blood thinning drugs including aspirin.

Is treatment possible?

Brain cells which have been destroyed cannot be repaired, and so the damage done to the brain by a stroke is permanent. However, the brain can sometimes find ways to function around damaged areas, and confusion after a stroke does sometimes improve.

People with vascular dementia should be offered a skilled multidisciplinary assessment of their condition through referral to a specialist. This service may be part of the general stroke service or the psychogeriatric service.

• People who have had strokes do better when seen by specialist multidisciplinary teams for treatment and rehabilitation focused on restoring as much mental or physical ability as possible.
• Specialist doctors can ensure accurate diagnosis so that any underlying disease, such as hypertension or diabetes, is treated.
• Speech and language therapists help someone make the best use of remaining abilities.
• An occupational therapist specialising in mental health can help someone cope better in daily life and be safer in the home.
• In severe cases nursing care may be needed.

October 1997

Page Text supplied by The Alzheimer's Disease Society of Great Britain