Multi-Infarct
Dementia
Multi-Infarct
Dementia
Definition:
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 (thrombi) 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.
Prevention:
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:
Return to TOP
Signs
and tests:
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 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, skull X-ray, or MRI of head may show changes that indicate
multi-infarct dementia.
Treatment:
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: The person 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 (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. 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.
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.
Return to TOP
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.
Calling
your health care provider:
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.
Call for an appointment with your health care provider if the condition
deteriorates to the point of inability to care for the person in the home.
Return to TOP
Back
To Other Dementias Directories
Back
to the Multi-Infarct Dementia Directory