Dementia
Dementia is a slow, progressive decline in mental function in which memory, thinking, judgment, and the ability to learn are impaired.
In the United States, an estimated 6 million people have dementia. Dementia occurs primarily in people older than age 65, affecting about 6 to 8% of people in this age group. More than 30% of those aged 85 or older (the most rapidly growing segment of the population) may have dementia. Nevertheless, dementia is never a normal part of aging. More than 50% of people older than 100 do not have dementia.
As people age, changes in the brain cause some decline in short-term memory and slowing in learning ability. These normal age-related changes, unlike dementia, do not affect the ability to function. Such memory loss in older people (sometimes called benign senescent forgetfulness or age-associated memory impairment) is not necessarily a sign of dementia or early Alzheimer's disease. Dementia is a much more serious decline in mental ability, and one that worsens with time. People who are aging normally may misplace things or forget details, but people who have dementia may forget entire events. People who have dementia have difficulty performing normal daily tasks such as driving, cooking, and handling finances.
Some older people develop a disorder that resembles dementia but is actually depression. It is called pseudodementia or the dementia of depression. People with pseudodementia eat and sleep little, and they complain bitterly about their memory loss, in contrast to people who have true dementia, who lack insight about their condition and often deny memory loss. People who have pseudodementia regain mental function after the depression is treated. Depression may also coexist with dementia. In such cases, treatment of depression may improve but not entirely restore mental function.
Causes
The most common cause of dementia is Alzheimer's disease. Other common causes are Lewy body dementia and destruction of brain tissue by strokes, which results in vascular dementia (multi-infarct dementia). Many people have more than one of these dementias (a condition called mixed dementia).
Less common causes include Parkinson's disease, infections such as AIDS, normal-pressure hydrocephalus, and drug or alcohol abuse. Rare causes of dementia are Pick's disease and Creutzfeldt-Jakob disease, including its variant form, which is thought to result from consuming contaminated meat. Dementia may also result from brain damage due to a head injury or from cardiac arrest (sudden stopping of the heart's pumping). Radiation therapy to the head as treatment for cancer (such as that for children with leukemia or for adults with a brain tumor) occasionally causes dementia that develops many months or years after treatment, as part of a condition called late radiation damage.
Sometimes dementia is worsened by disorders that can be modified. For example, diabetes, emphysema, or heart failure, if inadequately treated, can worsen dementia. Many people can be substantially helped when such disorders are treated or corrected. In about 10%, the symptoms of dementia can be completely reversed.
Many drugs may temporarily worsen the symptoms of dementia. Some of these drugs can be purchased without a prescription (over the counter). Sleep aids (which are sedatives), cold remedies, antianxiety drugs, and some antidepressants are common offenders. Drinking alcohol, even in moderate amounts, may also worsen dementia, and most experts recommend that people with dementia stop drinking alcohol.
Symptoms
In people with dementia, mental function typically deteriorates over a period of 2 to 10 years. However, dementia progresses at different rates depending on the cause. In people with vascular dementia, symptoms tend to worsen in steps, worsening suddenly with each new stroke, with some improvement in between. In people with Alzheimer's disease or Lewy body dementia, symptoms tend to worsen more steadily.
The rate of progression also varies from person to person. Looking back at how fast it worsened during the previous year often gives an indication about the coming year. Symptoms may worsen when people with dementia are moved to nursing homes or other institutions, because people with dementia have difficulty remembering and following rules and routines. Problems, such as pain, shortness of breath, retention of urine, and constipation, may cause delirium with rapidly worsening confusion in people who have dementia. If these problems are corrected, people usually return to the level of functioning they had before the problem.
Because dementia usually begins slowly and worsens over time, it may not be identified at first. Memory, especially for recent events, is one of the first mental functions to noticeably deteriorate. As dementia worsens, the ability to keep track of time and the ability to recognize people, places, and objects are reduced. People with dementia typically have problems finding and using the right word and have difficulty with abstract thinking (such as working with numbers). Emotions may be changeable, unpredictably and rapidly switching from happiness to sadness. Changes in personality are also common. Often, a particular personality trait becomes increasingly exaggerated: People who were always concerned with money become obsessed with it, or people who were often worried become constant worriers. Sleep patterns are often abnormal.
Some people with dementia hide their deficiencies well. They avoid complex activities such as balancing a checkbook, reading, and working. People who do not modify their lives may become frustrated with their inability to perform daily tasks. They may forget to do important tasks or may perform them incorrectly; for example, they may forget to pay bills or to turn off the lights or stove.
People with dementia may become withdrawn and less capable of controlling their behavior, sometimes acting disruptively (for example, by yelling, throwing, hitting, or wandering). Several effects of dementia contribute to these actions. Because people with dementia have difficulty understanding what they see and hear, they may misinterpret an offer of help as a threat and lash out. Because their short-term memory is impaired, they cannot remember what they are told or have done. They repeat questions and conversations, demand constant attention, or ask for things (such as meals) they have already received. Because they cannot express their needs clearly or at all, they may yell when in pain or wander when lonely or frightened. About 10% of people with dementia also have a psychosis, with hallucinations, delusions, or paranoia.
Eventually, people with dementia become unable to follow conversations and may become unable to speak. In its most advanced forms, dementia results in a near-complete destruction of the brain's ability to function. People become totally dependent on others, and many become bedridden. Eventually, people may have difficulty swallowing food without choking. Death often results from an infection, such as pneumonia.
Diagnosis
Forgetfulness is usually the first sign noticed by family members or doctors. Doctors and other health care practitioners can usually diagnose dementia by asking the person and family members a series of questions. The person is also given a mental status test, consisting of simple questions and tasks, such as naming objects, recalling short lists, writing sentences, and copying shapes (see Section 6, Chapter 77). More detailed testing (called neuropsychologic testing) is sometimes needed to clarify the degree of impairment or to determine whether the person is experiencing true mental decline. This testing covers all the main areas of mental function, including mood, and usually takes 1 to 3 hours.
Doctors diagnose dementia based on the person's age and family history, the development and progression of symptoms, the results of a neurologic examination (see Section 6, Chapter 77), and the presence of other disorders, such as brain damage due to a stroke or, in alcoholics, undernutrition.
Doctors search for treatable disorders that may be causing or contributing to the dementia. Examples are thyroid disorders, abnormal levels of electrolytes in the blood, infections, vitamin deficiencies (especially vitamin B12), toxicity due to a drug, and depression. Blood tests are performed, and doctors review all of the person's prescription drugs to see if one or more of them may be the cause. Doctors look for clues suggesting depression as a possible cause and ask questions about emotional health, especially with older people. Computed tomography (CT) or magnetic resonance imaging (MRI) is performed to rule out a brain tumor, normal-pressure hydrocephalus, and stroke.
Doctors also determine whether another, unrelated physical disorder or psychiatric disorder (such as schizophrenia) is also present, because treatment of these disorders may improve the general condition of people with dementia.
Treatment
For most dementias, no treatment can restore mental function. However, treating disorders that are worsening the dementia sometimes slows mental decline. For people who have dementia and depression, antidepressants (such as sertraline and paroxetine (see Section 7, Chapter 101)) and counseling may help, at least temporarily. Abstaining from alcohol can result in long-term improvement.
Environmental Measures: Creating a supportive environment can be remarkably helpful. People who have mild to intermediate dementia usually function best in familiar surroundings and can usually remain at home. Homes can be evaluated for safety by a visiting nurse agency and modified accordingly. For example, dim light can cause safety hazards and worsen the tendency of people with dementia to misinterpret what they see, so lighting should be relatively bright.
Structure and routine help people with dementia stay oriented and give them a sense of security and stability. Low-stress activities scheduled on a regular basis can help people feel independent and needed by focusing their attention on pleasurable or useful tasks. Such activities can also help relieve depression. Physical activity is particularly important because it helps prevent disruptive behavior, such as agitation and wandering. Continued mental activity, including hobbies, interest in current events, and reading, should be encouraged. Excessive stimulation should be avoided, but people should not be socially isolated. Some improvement may occur if daily routines are simplified, if expectations for people with dementia are realistic, and if they are enabled to maintain some sense of dignity and self-esteem.
Because dementia is usually progressive, planning for the future is essential. Such planning usually involves the efforts of a doctor, a social worker, nurses, and a lawyer, but most of the responsibility falls on family members. Decisions about moving a person with dementia to a more supportive environment involve balancing the desire to keep the person safe with the desire to maintain the person's sense of independence as long as possible. Such decisions depend on many factors, including the severity of the dementia, the home environment, availability of family members and caregivers, financial resources, and the presence of other, unrelated disorders and physical problems.
 See the sidebar Creating a Beneficial Environment for People With Dementia.
Drugs: Donepezil, galantamine, rivastigmine, and tacrine may improve mental function temporarily, but they do not slow the progression of dementia.
Antipsychotic drugs, such as haloperidol, olanzapine, and risperidone (see Section 7, Chapter 107), are often used to control the agitation and outbursts that may accompany advanced dementia. However, these drugs are not very effective for this purpose, and they can cause serious side effects. Antipsychotic drugs are most effective in people who have hallucinations, delusions, or paranoia in addition to dementia.
Many dietary supplements have been tried but have generally proved of little value in treating dementia. They include lecithin, ergoloid mesylates, and cyclandelate. Ginkgo biloba, a dietary supplement that is marketed as a memory enhancer, may modestly benefit some people with dementia (see Section 2, Chapter 19). Vitamin B12 supplements are effective only in people who have vitamin B12 deficiency, and thyroid hormone replacement is effective only in those who have an underactive thyroid gland (hypothyroidism).
End-of-Life Issues: Before dementia becomes too severe, decisions should be made about medical care and finances. People with dementia, if sufficiently able, should appoint a health care proxy (who is legally authorized to make treatment decisions on their behalf), and they should discuss health care wishes with their surrogate (proxy) and doctor (see Section 1, Chapter 8 and Section 1, Chapter 9).
As dementia worsens, treatment tends to be directed at maintaining the person's comfort rather than at attempting to prolong life. For example, the proxy and family members may have to make decisions about whether to allow artificial feeding or to treat an acute illness such as pneumonia. Such issues are best discussed with all concerned long before decisions are necessary.
See the sidebar Caring for Caregivers.
Alzheimer's Disease
Alzheimer's disease is a progressive, relentless loss of mental function, characterized by degeneration of brain tissue, including loss of nerve cells and the development of senile plaques and neurofibrillary tangles.
The most common cause of dementia is Alzheimer's disease. In older people, it accounts for up to 65% of dementias. It is very rare among people younger than 60. It becomes more common with increasing age. It affects only about 1% of people aged 60 to 64, but up to 30% of those older than 85. In the United States, about 4 million people have Alzheimer's disease.
What causes Alzheimer's disease is unknown, but genetic factors play a role: The disease seems to run in some families and is caused or influenced by several specific gene abnormalities. One abnormality affects apolipoprotein E (apo E)--the protein part of certain lipoproteins, which transport cholesterol through the bloodstream. There are three types of apo E (e2, e3, and e4). People with the e4 type develop Alzheimer's disease more commonly and at an earlier age than other people. In contrast, people with the e2 type seem to be protected against Alzheimer's disease. People with the e3 type are neither protected nor more likely to develop the disease. (These associations have been studied primarily in whites and may not apply to other races.) Genetic testing for apo E type cannot determine whether a person will develop Alzheimer's disease. Therefore, this testing is not routinely recommended.
In Alzheimer's disease, parts of the brain degenerate, destroying nerve cells and reducing the responsiveness of the remaining ones to many of the chemical messengers that transmit signals in the brain (neurotransmitters). Abnormalities in brain tissue consist of senile or neuritic plaques (clumps of dead nerve cells containing an abnormal, insoluble protein called amyloid) and neurofibrillary tangles (twisted strands of insoluble proteins in the nerve cell). Such abnormalities develop to some degree in all people as they age but are much more numerous in people with Alzheimer's disease.
Symptoms
Dementia resulting from Alzheimer's disease usually begins subtly. People whose disease develops while they are still employed may not perform as well in their jobs. In those who are retired and not very active, the changes may not be as noticeable. The first sign may be forgetting recent events, although sometimes the disease begins with depression, fears, anxiety, decreased emotion, or other personality changes. In the early stages, judgment and abstract thinking may be impaired. Speech patterns may change slightly; the person may use simpler words, use words incorrectly, or be unable to find the appropriate word. An inability to interpret visual cues may make driving a car difficult. People with Alzheimer's disease may be able to function socially but may behave unusually. For example, they may forget the name of a recent visitor, and their emotions may change unpredictably and rapidly. They may get lost on their way to the store.
As Alzheimer's disease progresses, people have trouble remembering events in the past. They may require help with eating, dressing, bathing, or going to the toilet. Wandering, agitation, irritability, hostility, and physical aggression are common. All sense of time and place is lost: People with Alzheimer's disease may even get lost on their way to the bathroom at home. Their increasing confusion puts them at risk of falling. Psychoses, with hallucinations, delusions, and paranoia, develop at some point in about half of people with Alzheimer's disease.
Eventually, people with Alzheimer's disease cannot walk or take care of their personal needs. They may be incontinent and unable to swallow, eat, or speak. These changes put them at risk of undernutrition, pneumonia, and bedsores (pressure sores). Memory is completely lost. Because these people become totally dependent on others, a nursing home may become necessary. Ultimately, coma and death, often due to infections, result.
Progression is unpredictable. The expected survival from the time the disorder is diagnosed ranges from 2 to 10 years, but usually 3 to 5 years. On average, people with Alzheimer's disease who can no longer walk live no more than 6 months.
Diagnosis
Doctors suspect Alzheimer's disease as the most likely cause of dementia in older people whose memory gradually deteriorates. Although a diagnosis based on examination of the person can be correct most of the time, the diagnosis of Alzheimer's disease is proved only by microscopic examination of brain tissue obtained during an autopsy. When brain tissue is examined, the characteristic loss of nerve cells, neurofibrillary tangles, and senile plaques containing amyloid can be seen throughout the brain but particularly in the area of the temporal lobe that is involved in the formation of new memories. Analysis of spinal fluid and positron emission tomography (PET (see Section 6, Chapter 77)) have been suggested as ways to diagnose Alzheimer's disease during life, but these procedures are not yet reliable in predicting who will develop Alzheimer's disease or in identifying people who already have it.
Treatment
General measures for treatment of Alzheimer's disease are the same as for all dementias (see Section 6, Chapter 83).
The use of certain drugs (such as nonsteroidal anti-inflammatory drugs [NSAIDs]) to prevent and slow the progression of Alzheimer's disease is under study. Estrogen and vitamin E may help prevent and slow progression of the disease, although study results are inconsistent. Before any of these substances are taken, their risks and benefits should be discussed with a doctor.
Donepezil, rivastigmine, tacrine, and galantamine increase the levels of the chemical messenger (neurotransmitter) acetylcholine, which may be low in many forms of dementia. These drugs may improve cognitive function temporarily, but they do not slow the progression of the disease. About half of the people who have Alzheimer's disease benefit from these drugs. For these people, the drugs effectively turn the clock back 6 to 9 months. These drugs are most effective in people with mild to moderate disease. Because the drugs are expensive and may have side effects, they should not be continued in people who do not benefit from them. The most common side effects include nausea, vomiting, weight loss, and abdominal pain or cramps. Side effects are usually mild and relatively uncommon with donepezil and galantamine.
An extract of ginkgo biloba (called EGb) has been claimed to have effects similar to those of the drugs described above (see Section 2, Chapter 19). However, further study of this medicinal herb is needed.
Lewy Body Dementia
Lewy body dementia is progressive loss of mental function due to specific changes in brain tissue, including the development of Lewy bodies in nerve cells and degeneration of part of the brain stem.
Lewy body dementia is a common cause of dementia, but experts disagree about its prevalence and significance. It is more common among men than among women. Microscopic changes in the brain differ from those due to Alzheimer's disease in that nerve cells develop abnormal structures called Lewy bodies. Lewy bodies also occur in Parkinson's disease. In Parkinson's disease, they occur only in one part of the brain, but in Lewy body dementia, they occur throughout the brain.
The symptoms of Lewy body dementia are very similar to those of Alzheimer's disease. However, people with Lewy body dementia tend to have more hallucinations, usually visual ones that are often complex and detailed, and they often have severe adverse reactions to antipsychotic drugs (see Section 7, Chapter 107). Another distinguishing feature is that in the early stages of the dementia, mental function varies from day to day, often dramatically. One day, people may be able to converse coherently, and the next day, they may be inattentive, drowsy, and almost mute. Like people who have Parkinson's disease, people with Lewy body dementia move slowly and sluggishly, shuffle when they walk, and stoop over.
The expected survival from the time symptoms begin is 6 to 12 years. There is no specific treatment for Lewy body dementia, but the same drugs used to treat Alzheimer's disease may be helpful. General measures for treatment are the same as those for all dementias.
Vascular Dementia
Vascular dementia (multi-infarct dementia) is mental dysfunction due to destruction of brain tissue by strokes, either a few large ones or many small ones.
A series of strokes may result in vascular dementia. These strokes are more common among men and usually begin after age 70. Risk factors for vascular dementia include high blood pressure and diabetes (both of which damage blood vessels in the brain). People who smoke or have smoked are also at risk.
The strokes gradually destroy brain tissue by blocking the blood supply to the brain. The areas destroyed are called infarcts. Small strokes cause little or no immediate weakness and seldom cause the paralysis that results from larger strokes.
Unlike dementia caused by Alzheimer's disease, vascular dementia may progress in steps, worsening suddenly but then improving somewhat, only to worsen again months or years later when another stroke occurs. Symptoms (memory loss, difficulty performing simple tasks, and a tendency to wander) are similar to those of other dementias, but judgment and personality may be affected less than in people with Alzheimer's disease. Symptoms can vary depending on what part of the brain is destroyed. Usually, some aspects of mental function are not impaired, because the strokes destroy tissue in only part of the brain.
The presence of neurologic signs that usually result from small strokes can help doctors identify vascular dementia. Signs include partial loss of sight, slow and slurred speech, weakness or paralysis of one leg, and difficulty walking.
General measures for treatment of vascular dementia are the same as those for all dementias (see Section 6, Chapter 83). Treating diabetes and high blood pressure can help prevent and slow or stop the progression of vascular dementia. Stopping smoking is also recommended.
There is no specific treatment for vascular dementia. Anticoagulants, which inhibit blood clotting, are given to some people who have had strokes to prevent additional strokes. Warfarin, a strong anticoagulant, is given to people who have an irregular heart rhythm, which increases the risk of strokes due to blood clots from the heart. Aspirin is beneficial for people who have had strokes caused by narrowed blood vessels that supply the brain.
Other Dementias
Dementia develops in many disorders. About 15 to 20% of people with Parkinson's disease develop dementia sooner or later.
Pick's disease, a rare disorder, is much like Alzheimer's disease except that it affects only a small area of the brain and progresses more rapidly. Symptoms include apathy, memory loss, carelessness, and poor personal hygiene.
Normal-pressure hydrocephalus develops when the cerebrospinal fluid that normally surrounds the brain and protects it from injury is not reabsorbed normally. The increasing amount of fluid around the brain puts pressure on brain tissue, causing an unusual type of dementia. Normal-pressure hydrocephalus causes not only loss of mental function but also urinary incontinence and an abnormally slow, unsteady, wide-legged walk. If diagnosed early, normal-pressure hydrocephalus can sometimes be treated by removing the excess fluid within the brain through a drainage tube (shunt). However, after this procedure, walking and continence often improve more dramatically than does mental function.
Creutzfeldt-Jakob disease, an infectious disease, causes a rare, rapidly progressive dementia due to an infection with a prion, an abnormal protein (see Section 6, Chapter 90). Usually Creutzfeldt-Jakob disease rapidly leads to severe dementia and death, often within a year. No treatment is available. Variant Creutzfeldt-Jakob disease, thought to be acquired from eating contaminated beef, causes a dementia similar to that due to Creutzfeldt-Jakob disease. It is also caused by a prion.
Dementia due to AIDS probably results from infection of the brain with the human immunodeficiency virus (HIV). This dementia usually begins subtly but progresses steadily over a few months or years. It usually develops after other symptoms of AIDS. Symptoms of this dementia include slowed thinking and expression, difficulty concentrating, and apathy. Movements are slow, and muscle weakness and lack of coordination may be present. Treatment with zidovudine and other drugs used to treat HIV infection sometimes produces dramatic improvement.
Dementia pugilistica (chronic progressive traumatic encephalopathy) may develop in people who have repeated head injuries--boxers, for example. They often develop symptoms similar to those of Parkinson's disease, and some of them also develop normal-pressure hydrocephalus.
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