Vascular Dementia
Disease Information
Dementia is the general term for a gradual progressive decline in a person's memory and other cognitive abilities. Vascular dementia is the second most common form of dementia after Alzheimer disease (AD) and accounts for up to a third of all dementias. This condition is not a single disease but a group of syndromes relating to different vascular mechanisms. Changes in the brain's blood supply may result in the erosion of some brain issue (neurons). The initiating event could be a single stroke, a number of small strokes, a temporary decrease in brain blood flow (transient ischemic attack/TIA) or a traumatic brain injury (TBI). Vascular dementia can also be caused by a number of other conditions including high blood pressure (hypertension), irregular heart rhythms (arrhythmias), cardiac arrest and diseases which cause damage to the blood vessels in the brain (arteriosclerosis).
Causes
Vascular dementia can be caused in several different ways.
- Most commonly there is blockage of small blood vessels (arteries) deep within the brain. When any part of the body is deprived of blood, which carries oxygen and nutrients, it dies - this is called an infarct or ischemia. When brain tissue dies it is also called necrosis.
- Blockages may be caused by build up of plaque on the inside of the arterial wall or by clots which have broken off, jamming a smaller tributary upstream. Clots can also result from abnormal heart rhythms, or other heart pathology, or can form on the inside of the major carotid arteries that run up the side of the neck and supply the brain.
- Rarer causes of vascular dementia are associated with auto-immune inflammatory diseases of the arteries such as systemic lupus erythermotsis (SLE or lupus) and temporal arteritis. Both of these can be treated with cortisone type drugs or other drugs to suppress the immune system.
- Finally, blood vessels may burst or hemorrhage. This is a dramatic event, often preceded or accompanied by severe headache, and leading to hospital admission. Defects are often severe. The patient's history allows ready diagnosis of this type of vascular dementia.
Types of Vascular Dementia
Vascular dementia is due to impaired blood supply to the brain and can be divided into different types depending on the nature of the vascular disease.
| Type | Description |
|---|---|
| Arteriosclerotic Dementia | Reduced oxygen supply to the brain (chronic ischemia) |
| Vascular Dementia | Following a stroke. Major strokes can be fatal or may lead to physical disability or vascular dementia due to damage to the brain |
| Multi-infarct Dementia (MID) | MID develops gradually following a number of mini-strokes or transient ischemic attacks, which the person may not realize they are having. MID, the most common form of vascular dementia, affects the cerebral cortex, which is the outer part of the brain |
| TIA | Temporary interruptions of blood flow to the brain, versus a stroke, which is a permanent cut off of blood to part of the brain. TIA warning signs include numbness, weakness, or paralysis of the face, arm or leg, especially on one side; sudden blurred, decreased or complete loss of vision in one or both eyes; difficulty speaking or understanding simple statements; loss of balance, dizziness or loss of co-ordination especially when combined with another warning sign, and sudden severe headache in one part of the head |
| Subcortical Vascular Dementia (Binswanger's Disease) | Involves vascular damage to the nerve cell fibers of the inner parts of the brain (deep white matter) by affecting the sheath which insulates nerve fibers in the brain (demyelization) |
| Strokes | Occur when brain cells are deprived of their blood supply and die. They can be caused by damage to the brain or neck arteries. The damage may be a blockage or bleeding into the brain caused by thrombosis, embolism or hemorrhage |
Prevention
Most causes are not preventable. Eating a low fat diet and exercising regularly may reduce the chances of vascular dementia, which is caused by repeated small strokes. Lowering high blood pressure and/or high cholesterol levels are managing the risk for both acute and chronic neurological disorders. Vascular dementia may also play a role in the pathogenesis of Alzheimer's disease.