A disorder involving deterioration in mental function caused by changes or damage to the brain tissues from lack of oxygen as a result of multiple blood clots throughout the brain.
Causes, incidence, and risk factors:
Multi-infarct dementia (MID) affects approximately 4 out of 10,000 people. It is estimated that 10 to 20% of all dementias are multi-infarct dementia (MID and Alzheimer's disease together account for about 30 to 60% of all dementia). MID affects both sexes but 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 an artery. 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 from 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 cause multiple, scattered blood clots that block off the small blood vessels and prevent localized areas of the brain from receiving blood flow and oxygen.
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 step-by-step manner to delirium, hallucinations, and impaired thinking. Personality and mood changes accompany the deteriorating mental condition. Apathy and lack of motivation are common. Catastrophic reaction, where a person reacts to tasks by withdrawal or extreme agitation, is common. Confusion that occurs or is worsened at night is also common.
Risks include a history of MID, stroke, hypertension, smoking, and atherosclerosis. Atherosclerosis is associated with coronary heart disease, cerebrovascular disease, peripheral vascular disease, diabetes mellitus, and kidney disorders that require dialysis. Risks of atherosclerosis include obesity, hypertension, and high levels of blood lipids, including cholesterol and triglycerides.
Control of conditions that increase the risk of atherosclerosis may help to reduce 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.
Additional symptoms that may be associated with this disease:
A neurologic examination shows variable deficits depending on the extent and location of damage. There may be multiple, 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, skull X-ray, or MRI of head may show changes that indicate multi-infarct dementia.
There is no known definitive treatment for MID. Treatment is based on control of symptoms. Other treatments may be advised based on the individual condition.
Initial diagnosis and treatment:
should be in a pleasant, comfortable, nonthreatening, 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, including treatment for atherosclerosis and hypertension.
Discontinuing or changing medications that worsen confusion or that are not essential to the care of the person may improve cognitive function. Medications that may cause confusion include anticholinergics, 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, 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. Medications may include antipsychotics, beta-blockers, serotonin-affecting drugs (lithium, trazodone, buspirone, or clonazepam), fluoxetine, imipramine, or others.
Sensory function should be evaluated and augmented as needed by hearing aids, glasses, or cataract surgery.
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.
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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