Vascular dementia occurs when the blood supply to the brain is inadequate. This reduces the supply of nutrients and oxygen to brain cells causing them to die off. This is usually due to blood vessel damage; either the blood vessel slowly blocks up, or clots form on the damaged blood vessel wall then break off and are carried into the brain where they lodge in a smaller vessel causing a stroke. Occasionally bleeding into the brain can cause vascular dementia.
Types of vascular dementia
Repeated Transient Ischemic Attacks (TIAs), or small strokes, can eventually do enough damage to the brain for dementia to become apparent. These events are often unnoticed by the person having them.
Multi-infarct dementia gradually worsens as more strokes occur. Between each stroke there is a plateau where symptoms are stable. This is called a “step-wise” progression. It can cause rapid mood changes, emotional overreactions, or depression.
Subcortical dementia is associated with damage to the small vessels deep in the brain. This causes changes in thinking, reasoning ability, memory, movement (including walking), behaviour and bladder control. The symptoms gradually worsen over time as more damage occurs.
Strategic-infarct dementia occurs when a single large stroke causes dementia. The symptoms will depend on which part of the brain was affected. A person may remain stable with this condition or even improve, but this will depend on the state of the brain’s blood supply and whether there are further strokes.
Who gets vascular dementia?
Vascular dementia is the second most common type of dementia after Alzheimer’s disease. The prevalence of vascular dementia increases with age and is higher in men than women. The risk factors for vascular dementia are the same as those for ischaemic heart disease:
- High blood pressure
- High cholesterol
If these factors are left untreated blood vessels will be damaged.
There are other factors, such as an irregular heartbeat or heart valve damage that can cause clots to form and travel to the brain as well as other rare forms of blood vessel damage. 20 to 30 percent of individuals develop dementia in the 3 months after a stroke. People with Alzheimer’s disease may also have vascular dementia in this case it is called “mixed” dementia.
Once a doctor has made the diagnosis of dementia, they will look for a cause. The characteristics of vascular dementia are:
- Lack of prominent memory symptoms
- Emotional changes
- A fluctuating decline in cognition
- Any evidence of vascular (blood vessel) problems.
Further neuropsychological testing can help distinguish vascular dementia from other forms of dementia and measure areas of cognitive strength and weakness.
A person’s medical history can reveal past heart attack, previous strokes, or brief neurological episodes (TIAs) such as brief slurring of speech, double vision, or collapses. A full physical examination may show stroke-related abnormalities of the nervous system, heart irregularities or murmurs, poor blood supply to the feet, or narrowing of the carotid arteries, the main blood supply to the brain.
Blood tests can show whether there is anything else causing the problem and whether there is anything likely to make things worse like diabetes. An electrocardiogram (ECG) will check for heart rhythm abnormalities and an echocardiogram of the heart looks for clots that might be going to the brain. An ultrasound of the carotid arteries in the neck looks for sources of clots that could go to the brain. CT or MRI scans help to find areas of brain damage and confirm that the blood supply is poor or that there have been strokes.
While there is no specific treatment for dementia it may be possible to improve the brain blood supply and to prevent more strokes. Dealing with any specific heart and blood vessel problems can help. This may require anticoagulant treatment such as warfarin or aspirin to stop clotting. Controlling high blood pressure, cholesterol, and diabetes will reduce blood vessel damage as will exercise, weight loss, a good diet, and stopping smoking.
The medications used for Alzheimer’s and Lewy Body dementia are not particularly useful in vascular dementia unless a person has a mixed form of dementia with either of those.