According to the Alzheimer's Association, vascular dementia is the second most common cause of dementia after Alzheimer’s disease (AD), accounting for an estimated 20 to 30 percent of all dementias. It is caused by brain damage from cerebrovascular or cardiovascular problems (usually stroke). It may also result from genetic diseases, endocarditis (infection of a heart valve) or amyloid angiopathy (a process in which amyloid protein builds up in the brain’s blood vessels, sometimes causing hemorrhagic or “bleeding” strokes). In many cases, vascular dementia may coexist with Alzheimer’s disease.
The hallmark sign of dementia, memory loss, may or may not occur as the primary indicator of vascular dementia. Symptoms depend on which area of the brain has been damaged. Stroke may reduce or block blood flow to regions of the brain, impacting thinking skills, speech, or movement and balance.
Symptoms of Vascular Dementia
Affected individuals frequently wander at night and often have other problems commonly found in people who have had a stroke, including depression and incontinence.
Symptoms often begin suddenly, usually after a stroke. Those at the highest risk have a history of high blood pressure, vascular disease, or previous strokes or heart attacks. Cognitive abilites may worsen over time if an individual experiences additional strokes. Vascular dementia often progresses in steps or stages characterized by sudden changes in ability.
When coupled with brain damage to the mid-brain regions, gradual, progressive cognitive impairment can occur that strongly resembles AD. Unlike elders with AD, those with vascular dementia often maintain their personality and normal levels of emotional responsiveness until the later stages of the disease.
Types of Vascular Dementia
There are several types, which vary slightly in their causes and symptoms.
Multi-Infarct Dementia (MID): This type is caused by numerous small strokes in the brain. MID typically includes multiple damaged areas called infarcts along with extensive lesions in the white matter or nerve fibers of the brain.
Single-Infarct Dementia: Not all strokes cause cognitive problems, but in some cases a single massive stroke can damage a specific area of the brain enough to cause dementia. This is more common when the stroke takes place on the left side (hemisphere) of the brain and/or when it involves the hippocampus, a brain structure important for memory.
Binswanger’s Disease: This is a rare type characterized by damage to small blood vessels in the white matter of the brain. The white matter is found in the inner layers of the brain and contains many nerve fibers coated with a whitish, fatty substance called myelin. Binswanger’s leads to brain lesions, loss of memory, disordered cognition and mood changes.
People with Binswanger’s often show signs of abnormal blood pressure, stroke, blood abnormalities, disease of the large blood vessels in the neck and/or disease of the heart valves. Other prominent features include urinary incontinence, difficulty walking, clumsiness, slowness, lack of facial expression and speech difficulty. These symptoms, which usually begin after the age of 60, are not always present in all people and may sometimes appear only temporarily. Treatment of Binswanger’s is symptomatic and may include the use of medications to control high blood pressure, depression, heart arrhythmias and low blood pressure. The disorder often includes episodes of partial recovery.
CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarct and leukoencephalopathy): This type is linked to a rare hereditary disorder characterized by abnormalities of a specific gene, Notch3, which is located on chromosome 19. This condition causes MID as well as stroke, migraine with aura and mood disorders. The first symptoms usually appear in people who are in their twenties, thirties or forties. Affected individuals often die by age 65. Researchers believe most people with CADASIL go undiagnosed, and the actual prevalence of the disease is not yet known.
Other vascular causes include vasculitis (an inflammation of the blood vessel system), profound hypotension (low blood pressure) and lesions caused by brain hemorrhage. The autoimmune disease lupus erythematosus and the inflammatory disease temporal arteritis can also damage blood vessels in a way that may lead to a vascular dementia diagnosis.
Managing Vascular Dementia
Like other types of dementia, there is no cure for vascular dementia. Controlling risk factors that increase the likelihood of further damage to the brain’s blood vessels is an important prevention and treatment strategy. Physical exercise, maintaining a healthy weight and managing chronic health problems, such as diabetes, high blood pressure and high cholesterol are known to reduce the risk of heart problems and stroke.