What are some of the symptoms, treatment, and life expectancy for someone who suffers from a kind of dementia?

Definition
Dementia is not a specific disorder or disease. It is a syndrome (group of symptoms) associated with a progressive loss of memory and other intellectual functions that is serious enough to interfere with performing the tasks of daily life. Dementia can occur to anyone at any age from an injury or from oxygen deprivation, although it is most commonly associated with aging. It is the leading cause of institutionalization of older adults.

Description
The definition of dementia has become more inclusive over the past several decades. Whereas earlier descriptions of dementia emphasized memory loss, the last three editions of the professional’s diagnostic handbook, Diagnostic and Statistical Manual of Mental Disorders(also known as the DSM) define dementia as an overall decline in intellectual function, including difficulties with language, simple calculations, planning and judgment, and motor (muscular movement) skills as well as loss of memory. Although dementia is not caused by aging itself- most researchers regard it as resulting from injuries, infections, braindiseases, tumors, or other disorders- it is quite common in older people. The prevalence of dementia increases rapidly with age; it doubles every five years after age 60. Dementia affects only 1% of people aged 60- 64 but 30%- 50% of those older than 85. About four to five million persons in the United States are affected by dementia as of 2002. Surveys indicate that dementia is the condition most feared by older adults in the United States.

Causes and symptoms
Causes
Dementia can be caused by nearly forty different diseases and conditions, ranging from dietary deficiencies and metabolic disorders to head injuries and inherited diseases. The possible causes of dementia can be categorized as follows:

Primary dementia. These dementias are characterized by damage to or wasting away of the brain tissue itself. They include Alzheimer’s disease(AD), frontal lobe dementia (FLD), and Pick’s disease. FLD is dementia caused by a disorder (usually genetic) that affects the front portion of the brain, and Pick’s disease is a rare type of primary dementia that is characterized by a progressive loss of social skills, language, and memory, leading to personality changes and sometimes loss of moral judgment.
Multi-infarct dementia (MID). Sometimes called vascular dementia, this type is caused by blood clots in the small blood vessels of the brain. When the clots cut off the blood supply to the brain tissue, the brain cells are damaged and may die. (An infarct is an area of dead tissue caused by obstruction of the circulation.)
Lewy body dementia. Lewy bodies are areas of injury found on damaged nerve cells in certain parts of the brain. They are associated with Alzheimer’s and Parkinson’s disease, but researchers do not yet know whether dementia with Lewy bodies is a distinct type of dementia or a variation of Alzheimer’s or Parkinson’s disease.
Dementia related to alcoholism or exposure to heavy metals (arsenic, antimony, bismuth).
Dementia related to infectious diseases. These infections may be caused by viruses (HIV, viral encephalitis); spirochetes (Lyme disease, syphilis); or prions (Creutzfeldt-Jakob disease). Spirochetes are certain kinds of bacteria, and prions are protein particles that lack nucleic acid.
Dementia related to abnormalities in the structure of the brain. These may include a buildup of spinal fluid in the brain (hydrocephalus); tumors; or blood collecting beneath the membrane that covers the brain (subdural hematoma).
Dementia may also be associated with depression, low levels of thyroid hormone, or niacin or vitamin B 12deficiency. Dementia related to these conditions is often reversible.

Genetic factors in dementia
Genetic factors play a role in several types of dementia, but the importance of these factors in the development of the dementia varies considerably. Alzheimer’s disease (AD) is known, for example, to have an autosomal (non-sex-related) dominant pattern in most early-onset cases as well as in some late-onset cases, and to show different degrees of penetrance (frequency of expression) in late-life cases. Moreover, researchers have not yet discovered how the genes associated with dementia interact with other risk factors to produce or trigger the dementia. One non-genetic risk factor presently being investigated is toxic substances in the environment.

EARLY-ONSET ALZHEIMER’S DISEASE.In early-onset AD, which accounts for 2%- 7% of cases of AD, the symptoms develop before age 60. It is usually caused by an inherited genetic mutation. Early-onset AD is also associated with Down syndrome, in that persons with trisomy 21 (three forms of human chromosome 21 instead of a pair) often develop early-onset AD.

LATE-ONSET ALZHEIMER’S DISEASE.Recent research indicates that late-onset Alzheimer’s disease is a polygenic disorder; that is, its development is influenced by more than one gene. It has been known since 1993 that a specific form of a gene (the APOE gene) on human chromosome 19 is a genetic risk factor for late-onset AD. In 1998 researchers at the University of Pittsburgh reported on another gene that controls the production of bleomycin hydrolase (BH) as a second genetic risk factor that acts independently of the APOE gene. In December 2000, three separate research studies reported that a gene on chromosome 10 that may affect the processing of a protein (called amyloid-beta protein) is also involved in the development of late-onset AD. When this protein is not properly broken down, a starchy substance builds up in the brains of people with AD to form the plaques that are characteristic of the disease.

MULTI-INFARCT DEMENTIA (MID).While the chief risk factors for MID are high blood pressure, advanced age, and male sex, there is an inherited form of MID called CADASIL, which stands for cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. CADASIL can cause psychiatric disturbances and severe headaches as well as dementia.

FRONTAL LOBE DEMENTIAS.Researchers think that between 25% and 50% of cases of frontal lobe dementia involve genetic factors. Pick’s dementia appears to have a much smaller genetic component than FLD. It is not yet known what other risk factors combine with inherited traits to influence the development of frontal lobe dementias.
Treatments
Reversible and responsive dementias
Some types of dementia are reversible, and a few types respond to specific treatments related to their causes. Dementia related to dietary deficiencies or metabolic disorders is treated with the appropriate vitamins or thyroid medication. Dementia related to HIV infection often responds well to zidovudine (Retrovir), a drug given to prevent the AIDS virus from replicating. Multi-infarct dementia is usually treated by controlling the patient’s blood pressure and/or diabetes; while treatments for these disorders cannot undo damage already caused to brain tissue, they can slow the progress of the dementia. Patients with alcohol-related dementia often improve over the long term if they are able to stop drinking. Dementias related to head injuries, hydrocephalus, and tumors are treated by surgery.

It is important to evaluate and treat elderly patients for depression, because the symptoms of depression in older people often mimic dementia. This condition is sometimes called pseudodementia. In addition, patients who suffer from both depression and dementia often show some improvement in intellectual functioning when the depression is treated. The medications most often used for depression related to dementia are the selective serotonin reuptake inhibitors (SSRIs) paroxetineand sertraline. The mental status examination should be repeated after six- 12 weeks of antidepressant medication.

Irreversible dementias
As of 2001, there are no medications or surgical techniques that can cure Alzheimer’s disease, the frontal lobe dementias, MID, or dementia with Lewy bodies. There are also no “magic bullets” that can slow or stop the progression of these dementias. There is, however, one medication, Aricept, that is being used to halt the progression of Alzheimer’s disease. In addition, another medication called galantamine(Reminyl) is also being used to treat the symptoms of Alzheimer’s disease. Patients may be given medications to ease the depression, anxiety, sleep disturbances, and other behavioral symptoms that accompany dementia, but most physicians prescribe relatively mild dosages in order to minimize the troublesome side effects of these drugs. Dementia with Lewy bodies appears to respond better to treatment with the newer antipsychotic medications than to treatment with such older drugs as haloperidol(Haldol).

Patients in the early stages of dementia can often remain at home with some help from family members or other caregivers, especially if the house or apartment can be fitted with safety features (handrails, good lighting, locks for cabinets containing potentially dangerous products, nonslip treads on stairs, etc.). Patients in the later stages of dementia, however, usually require skilled care in a nursing home or hospital.

Prognosis
The prognosis for reversible dementia related to nutritional or thyroid problems is usually good once the cause has been identified and treated. The prognoses for dementias related to alcoholism or HIV infection depend on the patient’s age and the severity of the underlying disorder.

The prognosis for the irreversible dementias is gradual deterioration of the patient’s functioning ending in death. The length of time varies somewhat. Patients with Alzheimer’s disease may live from two- 20 years with the disease, with an average of seven years. Patients with frontal lobe dementia or Pick’s disease live on average between five and 10 years after diagnosis. The course of Creutzfeldt-Jakob disease is much more rapid, with patients living between five and 12 months after diagnosis.

Prevention
The reversible dementias related to thyroid and nutritional disorders can be prevented in many cases by regular physical checkups and proper attention to diet. Dementias related to toxic substances in the workplace may be prevented by careful monitoring of the work environment and by substituting less hazardous materials or substances in manufacturing processes. Dementias caused by infectious diseases are theoretically preventable by avoiding exposure to the prion, spirochete, or other disease agent. Multi-infarct dementia may be preventable in some patients by attention to diet and monitoring of blood pressure. Dementias caused by abnormalities in the structure of the brain are not preventable as of 2002.

With regard to genetic factors, tests are now available for the APOE gene implicated in late-onset Alzheimer’s, but these tests are used primarily in research instead of clinical practice. One reason is that the test results are not conclusive; about 20% of people who eventually develop AD do not carry this gene. Another important reason is the ethical implications of testing for a disease that presently has no cure. These considerations may change, however, if researchers discover better treatments for primary dementia, more effective preventive methods, or more reliable genetic markers.