What Are The Other Dementias?
Although Alzheimer's is the most common cause of dementia, there are other diseases that produce dementia also. Though some are rare, others are more well-known. Here is a short description of a few.
Multi-infarct dementia, or vascular dementia, is mental deterioration caused by multiple strokes [infarcts] in the brain. The onset of MID may be relatively sudden as many strokes can occur before symptoms appear. These strokes may damage areas of the brain responsible for a specific function, such as calculations, and there may be more generalized symptoms, such as disorientation, confusion, and behavioral changes. As a result, MID may appear similar to Alzheimer's disease. In fact, MID and Alzheimer's co-exist in 15 to 20 percent of dementia people.
Brain scanning techniques [CAT, MRI] are used to identify strokes in the brain. MID progresses in downhill steps with periods of stability and possibly some slight improvement between strokes.
Histories of high blood pressure, vascular disease, diabetes, or previous strokes have been identified as risk factors. MID is not reversible or curable, but recognition of an underlying condition [for example high blood pressure] often leads to specific treatment that may halt the progression of the disorder.
Individuals with Parkinson's disease lack the substance dopamine, which is involved in control of muscle activity by the nervous system. Tremor, stiffness, and slowness are characteristic features of Parkinson's disease. Speech is slow. Movement may be difficult to initiate. Late in the course of the disease some people develop dementia. Some PD people develop Alzheimer's disease and some Alzheimer's people develop Parkinson's symptoms. Parkinson's drugs can improve the motor symptoms, but do not improve the mental changes that occur. In fact, Parkinsons's serves as a model for drug research on Alzheimer's disease.
Huntington's disease [HD] is a hereditary disorder that usually begins in mid-life and is characterized by irregular involuntary movements of the limb or facial muscles and intellectual decline. Psychiatric problems are common, with depression and memory disturbances occurring in the early stages. The pattern of memory impairment differs from that see in Alzheimer's disease. As the disease progresses, movements become severe and uncontrollable, mental capacity may deteriorate to dementia. The family history of the disease, recognition of typical movement disorders, and brain scanning provides evidence for the diagnosis of Huntington's disease. A genetic marker linked to the Huntington's gene has been identified on chromosome 4. Researchers are working on locating the gene itself. The movement disorders and psychiatric symptoms seen in HD can be controlled by drugs, however no treatment is available to stop progression of the disease.
Creutzfeld-Jakob disease is a rare fatal brain disease caused by a transmissible agent, possibly a virus. Failing memory, changes in behavior , and lack of coordination are some of the symptoms in the early stages of the disease. The disease progresses rapidly, usually causing death within one year of diagnosis. Examination of brain tissue reveals distinct changes unlike those seen in Alzheimer's disease. No treatment is currently available to stop the progression of the disease.
Pick's disease is a rare brain disease which closely resembles Alzheimer's disease and is usually difficult to diagnosis clinically. Disturbances in personality, behavior, and orientation may precede and initially be more severe than memory defects. Like Alzheimer's a definitive diagnosis is usually made at autopsy.
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