| Definition: |
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The most common form of vascular dementia, which is a deterioration in mental function caused by narrowing of blood vessels in the brain. This narrowing results from an accumulation of atherosclerotic plaques in these vessels. "Multi-infarct" means that there are numerous areas where this process has killed or damaged cells.
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| Causes, incidence, and risk factors: |
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MID affects approximately 4 out of 10,000 people. It is estimated that 10 to 20% of all dementias are caused by blood vessel (vascular) narrowing, making MID the third most common cause of dementia in the elderly, behind Alzheimer's disease and Dementia of Lewy Bodies (DLBD). MID affects men more often than women. The disorder usually affects older people, over 55 years, with the onset averaging around age 65.
The disorder is associated with atherosclerosis, a condition where fatty deposits occur in the inner lining of the arteries. Atherosclerotic plaque damages the lining of arteries. Platelets clump around the area of injury (a normal part of the clotting and healing process). Cholesterol and other fats also collect at this site, forming a mass within the lining of the artery. MID is not caused directly by the deposits of atherosclerotic plaque in the blood vessels of the brain, but by a series of strokes that leave areas of dead brain cells (infarction). This occurs when atherosclerotic plaques facilitate the formation of blood clots (thrombi) that block off the small blood vessels and prevent localized areas of the brain from receiving nutrients and oxygen from the blood flow that supplies them.
The consequences vary depending on the location and severity of the infarctions. Memory impairment is often an early symptom of the disorder, followed by judgment impairment. This often progresses in a stepwise manner to delirium, hallucinations and impaired thinking. Personality and mood changes accompany the deteriorating mental condition. Apathy and lack of motivation are common. Catastrophic reactions, where a person becomes withdrawn or extremely agitated, are also common. Confusion that occurs or is worsened at night is another common symptom.
Risk factors that make the development of MID likely include a history of stroke, hypertension, smoking and atherosclerosis. Atherosclerosis is the cause of numerous serious vascular problems, including heart attacks, cerebrovascular diseases, and peripheral vascular diseases (affected vessels are outside major organs, especially in the limbs), and may be associated with conditions such as diabetes mellitus, obesity, high cholesterol, and kidney disorders that require dialysis.
Some research suggests that MID may help cause or hasten the progression of Alzheimer's disease. MID may be misdiagnosed as Alzheimer's or found in addition to Alzheimer's disease. Since the difference cannot always be determined without brain biopsy and since there is little effective treatment for either condition, the distinction is mainly useful to researchers, not patients. However, once more carefully targeted therapies become available, the independent contribution of MID and Alzheimer's disease to the burden of dementia might become important to tailor these treatments accordingly in affected individuals.
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| Symptoms: |
- awareness of mental deterioration, if present:
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dementia (slowly progressive memory loss) is more commonly associated with lack of awareness of mental deterioration and:
- withdrawal from social interaction
- inability to interact in social or personal situations
- inability to maintain employment
- decreased ability to function independently
- decreased interest in daily living activities
- lack of spontaneity
- localized numbness or tingling
- swallowing difficulty
- sudden involuntary laughing or crying
- emotional instability, frequent changes of emotion
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urinary incontinence
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| Signs and tests: |
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The disorder is diagnosed based on history, symptoms, signs, and tests, and by ruling out other causes of dementia, including dementia due to metabolic causes. History may include a history of stroke or hypertension. History of the dementia often shows stepwise progression of the condition: periods of abrupt decline alternating with "plateau" periods of minimal decline. Other characteristics that suggest multi-infarct dementia rather than Alzheimer's disease include: abrupt onset, somatic (physical) complaints, emotional changes, and focal (localized) neurologic signs and symptoms (modified Hachinski ischemia scale).
A neurologic examination shows variable deficits depending on the extent and location of damage. There may be multiple, focal neurologic deficits (localized areas with specific loss of function). Weakness or loss of function may occur on one side or only in one area. Abnormal reflexes may be present. There may be signs of cerebellar dysfunction such as loss of coordination.
A head CT scan, and even more likely, MRI of the brain may show changes that suggest multi-infarct dementia because areas of dead tissue may be visible.
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| Treatment: |
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There is no known definitive treatment for MID. Treatment is based on control of symptoms and the correction of the precipitating risk factors (high blood pressure and high cholesterol, especially). Other treatments may be advised based on the individual condition.
INITIAL DIAGNOSIS AND TREATMENT:
The person should be in a pleasant, comfortable, non-threatening, physically safe environment for diagnosis and initial treatment. Hospitalization may be required for a short time. The underlying causes should be identified and treated as appropriate.
Discontinuing or changing medications that worsen or even induce confusion or that are not essential to the care of the person may improve cognitive function. Medications that may cause confusion include anticholinergics (including antidepressants with anticholinergic properties, such as amitriptyline or imipramine), analgesics, cimetidine, central nervous system depressants, lidocaine, and other medications.
Disorders that contribute to confusion should be treated as appropriate. These may include heart failure, decreased oxygen (hypoxia), thyroid disorders, anemia, nutritional disorders, infections and psychiatric conditions such as depression. Correction of coexisting medical and psychiatric disorders often greatly improves the mental functioning.
Medications may be required to control aggressive or agitated behaviors or behaviors that are dangerous to the person or to others. These are usually given in very low doses, with adjustment as required. Such medications may include antipsychotics (especially the newer atypical agents, olanzapine and quetiapine), beta-blockers, and serotonin-affecting drugs such as trazodone (which may lower the blood pressure), buspirone or fluoxetine.
It is important to note that the cholinergic medications currently recommended for Alzheimer's disease (namely donepezil [aricept] and rivastigmine [exelon]) are not beneficial in the treatment of vascular dementias. There is no data about the newest agent in this family of drugs (galantamine) although it has a similar mechanism of action and therefore would not be expected to improve symptoms due to multiple infarcts. Even when used to treat properly-diagnosed Alzheimer's disease, these medications only moderately slow, but do not prevent progression.
Sensory function should be evaluated and augmented as needed by hearing aids, glasses or cataract surgery.
LONG-TERM TREATMENT:
Provision of a safe environment, control of aggressive or agitated behavior and the ability to meet physiologic needs may require monitoring and assistance in the home or in an institutionalized setting. This may include in-home care, boarding homes, adult day care or convalescent homes. Family counseling may help in coping with the changes required for home care. Visiting nurses or aides, volunteer services, homemakers, adult protective services and other community resources may be helpful in caring for the person with MID. In some communities, there may be access to support groups.
In any care setting, there should be familiar objects and people. Lights that are left on at night may reduce disorientation. The schedule of activities should be simple.
Behavior modification may be helpful for some persons in controlling unacceptable or dangerous behaviors. This consists of rewarding appropriate or positive behaviors and ignoring inappropriate behaviors (within the bounds of safety). Reality orientation, with repeated reinforcement of environmental and other cues, may help reduce disorientation.
Legal advice may be appropriate early in the course of the disorder. Advance directives, power of attorney, and other legal actions may make it easier to make ethical decisions regarding the care of the person with MID.
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| Expectations (prognosis): |
The disorder is characterized by a downward course with intermittent periods of rapid deterioration. Death may occur from stroke, heart disease, pneumonia, or other infection.
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| Complications: |
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stroke
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atherosclerotic heart disease
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pneumonia
- infection
- reduced life span
- loss of ability to function or care for self
- loss of ability to interact
- increased incidence of infections anywhere in the body
- abuse by an over-stressed caregiver
- side effects of medications
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| Calling your health care provider: |
A routine visit to your health care provider should be made soon after any symptoms suggestive of vascular dementia appear. Go to the emergency room or call the local emergency number (such as 911) if a sudden change in mental status develops. This is an emergency symptom of stroke and should be thought of as a "brain attack" as it may represent the brain equivalent of a heart attack. If treated early, damage related to larger strokes involved in MID (which produce symptoms and rapid progression) may possibly be reduced. This can only be done, however, within three hours of the onset of symptoms.
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| Prevention: |
Control of conditions that increase the risk of atherosclerosis may help in reducing the risk of MID. This may include treatment of related disorders, weight loss, control of high blood pressure and dietary changes to reduce saturated fats or salt.
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