[Editor's note: This article is from 2007. Some newer treatments and current statistics are not included here. See further information on BrainWeb]
sections include: arrestable or reversible causes of dementia, progressive and nonreversible causes of dementia, diagnosing and treating dementia
Dementia is a group of symptoms involving the progressive impairment of many aspects of brain function at once, particularly in those parts of the cerebrum known as the association areas, which integrate perception, thought, and purposeful action. Doctors make the diagnosis of dementia when a person displays impairment of two or more brain functions, one of which must be memory. Other cognitive impairments can include deterioration in language (aphasia), voluntary movement (apraxia), the ability to recognize or identify objects (agnosia), and the ability to think abstractly and perform complex behaviors.
The causes and symptoms of dementia are many, varied, and often multiple. The most common causes involve impairment to the vascular (blood vessel) or neurological structures of the brain. Some of this damage is progressive and irreversible, while other problems can be stopped or reversed. Dementia can occur at all ages but is most likely to arise among older age groups, especially in people over 75.
Dementia usually appears first as memory loss. Individuals with dementia become impaired in their ability to learn new material, or they may forget previously learned material. They might leave the stove on, lose their keys repeatedly, or forget their own phone numbers. They may have difficulty remembering the names of objects or people, or find it difficult to speak coherently or understand what others say. Some are unable even to pantomime common actions, such as waving good-bye.
Loss of functioning progresses slowly, from decreased problem solving and language skills, to difficulty with ordinary daily activities, and on to severe memory loss and complete disorientation with withdrawal from social interaction. A person may not be aware of his or her dementia, however. Hallucinations, delusions, and paranoid behavior may occur.
All too often the signs of dementia, including types that can be treated, are dismissed as a normal result of aging. While we do undergo some cognitive changes as we age, dementia is a symptom of disease and must be diagnosed and treated as such.
Arrestable or Reversible Causes of Dementia
Causes of dementia that can be stopped or reversed include reactions to drugs, including those used as medications. Neuroactive and psychoactive agents, the opiate analgesics, the adrenocortical steroids, and anticholinergic preparations used for movement disorders have all been known to produce dementia. Some individuals have allergic reactions to certain drugs or combinations of them. In addition, alcohol and almost all other drugs that people abuse, ranging from heroin to glue, can cause dementia.
Brain infections can also cause dementia, including forms of meningitis, encephalitis, and syphilis, if untreated. Certain chronic viral illnesses, such as AIDS, can produce the symptom. For most of these illnesses, we have treatments. But the infectious prion responsible for the rare Creutzfeldt-Jakob disease can produce extreme dementia that is untreatable.
Metabolic causes of dementia are often treatable. Diseases of the thyroid, parathyroid, adrenals, and pituitary are often easy to identify and treat. When dementia is the result of kidney and liver failure, or the complications of diabetes, addressing the underlying cause often relieves the problem. Dehydration is another common, and easily treated, metabolic cause. Nutritional disorders, including thiamine deficiency, pernicious anemia, and folate deficiency, are usually preventable and sometimes reversible if recognized early.
Hypertension, or chronic high blood pressure, is one of the most frequent causes of dementia. Other vascular and cardiac diseases can also produce dementia by obstructing the blood supply to the brain. Treating the underlying problem can stop and sometimes reverse these dementias.
Tumors of the brain, both benign and malignant, frequently produce dementia. Surgical treatment depends on the size and location of the tumor. Normal pressure hydrocephalus, which is a rare cause of dementia, can often be relieved with a shunt.
Head injuries can result in dementia. When the trauma occurs once, as in a car accident or bad fall, the dementia can usually be stopped, but repeated head injury (such as a boxer might experience) can lead to progressive dementia.
Severe depression can also produce dementia. Treating the emotional disorder usually reverses the cognitive problems as well.
Progressive and Nonreversible Causes of Dementia
There are also progressive and nonreversible causes of dementia. We can divide these into two categories: those that have dementia as the primary symptom, and those that have other neurological signs.
Alzheimer’s, the most common of all dementing diseases, is discussed here. Pick’s disease, or frontotemporal dementia (FTD), is the other condition in this category, but it is far less common than Alzheimer’s. (For every person with Pick’s disease, there are probably 20 or 30 with Alzheimer’s.)
The initial symptoms of Pick’s disease are not thought to include memory losses, but some recent studies say that memory may be variably affected. More often the disorder appears in personality changes, which can differ from person to person. Some people exhibit apathy, while others lose their inhibitions and become overactive. Many develop eating disorders and gain weight, but some display ritualistic behavior (grunting, hand rubbing, foot tapping) and compulsions. Language impairment is the other common sign of FTD. Some people can speak only with great effort, and not fluently; for others, speech is fluent but lacks content. There is also a change in social conduct. Individuals lack insight and lose some of their sense of responsibility. In many cases, psychiatrists are the first doctors to see people with FTD because they are thought to be suffering from depression or psychosis.
Pick’s disease involves atrophy of the frontal and temporal lobes of the brain. The neurons in the affected areas come to contain abnormal material, called Pick’s bodies. Unlike Alzheimer’s, there are no plaques or intracellular fibers. We do not know the exact cause of this condition.
Pick’s disease typically begins between the ages of 35 and 75 and affects men and women equally. No treatments influence its progressive nature, and no surgical procedures are useful. The average course of illness spans ten years from first symptoms until death, but this period is quite variable.
The second category of progressive and nonreversible dementias includes a multitude of diseases of the nervous system in which dementia may or may not occur alongside other symptoms. These include Parkinson’s disease and Huntington’s disease, among other diseases affecting the basal ganglia, the cerebellum, and the motor neurons. Even taken all together, these other causes of dementia do not compare to the very great frequency of Alzheimer’s disease.
Diagnosing and Treating Dementia
Since the causes of dementia are many and varied, and some types can be stopped or reversed, the diagnosis must be careful and accurate. Diagnosis is complicated, however, because many dementia-causing diseases, such as Alzheimer’s, can only be confirmed or ruled out with certainty at autopsy.
Since people with dementia may not know that they are experiencing cognitive difficulties, family members are sometimes the first to notice such symptoms as minor forgetfulness, restlessness or apathy, a tendency to misplace things, or changes in personality and to bring them to the attention of a doctor. A physician with knowledge of dementia and dementia-causing diseases should perform a careful clinical evaluation. This should include a family history and a chronological account of the person’s illness that emphasizes the onset, duration, and specific cognitive, memory, and behavioral changes.
Physicians can use physical, neurological, and psychological evaluations to ascertain not only the primary cause (or causes) of a person’s dementia, but also possible coexisting abnormalities that might make the condition worse. These tests might include:
- complete blood count
- electrolyte measurements
- screening metabolic panel
- thyroid function tests
- checks for vitamin B12 and folate levels
- tests for syphilis and HIV antibodies
- chest X ray
- brain imaging
These tests can reveal most of the readily reversible causes of dementia, such as metabolic problems, nutritional deficiencies, and infections. Brain imaging (computed tomography, magnetic resonance imaging, or positron-emission tomography may also be appropriate. Neuroimaging may detect atrophy and perhaps characteristic patterns of decreased blood flow or metabolism in crucial regions.
In treating dementia, a doctor’s goal is to control the symptoms. Because they arise from different causes, that treatment varies with the specific disorder. If at all possible, physicians try to identify and treat the underlying causes, not just the symptom. Stopping or changing medications that worsen a person’s confusion and are not essential may improve his or her cognitive function. Addressing coexisting medical and psychiatric disorders—for example, treating hypothyroidism with replacement therapy, or treating depression—often greatly improves mental functioning. However, the clinical response to the commonly used anticholinesterase drugs (used for Alzheimer’s disease) is modest in terms of improving memory function.
People with dementia may have to take medications to control behaviors that are dangerous to themselves or others. Antipsychotic drugs, antianxiety drugs, and antidepressants are all used to treat the behavioral manifestations of dementia. These are usually given in very low doses and are adjusted as required.
Individuals with progressive dementia may be helped by visiting nurses, volunteer services, support groups, adult protective services, and other community resources. As the disease progresses, a person 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.
Research into the diagnosis and treatment of dementia continues. Advances in genetics and molecular biology may prove helpful in identifying potential biological markers. The most promising paths of research into Pick’s disease focus on its genetic bases, and in particular on the mutated tau gene.
back to top