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Dementia is a loss of mental ability severe enough to interfere with normal activities of daily living, lasting more than six months, not present since birth, and not associated with a loss or alteration of consciousness.


Dementia is a group of symptoms caused by gradual death of brain cells. The loss of cognitive abilities that occurs with dementia leads to impairments in memory, reasoning, planning, and behavior. While the overwhelming number of people with dementia are elderly, dementia is not an inevitable part of aging; instead, dementia is caused by specific brain diseases. Alzheimer's disease (AD) is the most common cause, followed by vascular or multi-infarct dementia.
The prevalence of dementia is difficult to determine, partly because of differences in definition among different studies and partly because there is some normal decline in functional ability with age. The prevalence of dementia roughly doubles for every five years of age beginning at age 60. Dementia affects about 1% of people between ages 60 and 64, 5-8% of all people between ages 65 and 74, up to 20% of those between 75 and 84, and between 30% and 50% of those age 85 and older. About 60% of nursing home patients have dementia. The Alzheimer's Association estimates that in 2007, 5.1 million Americans were living with a diagnosis of AD. That number expected to grow substantially as the population ages.
The cost of dementia can be considerable. While most people with dementia are retired and are not affected by income losses from their disease, the cost of care often is enormous. Financial burdens include lost wages for family caregivers, medical supplies and drugs, and home modifications to ensure safety. Nursing home care may cost several thousand dollars a month or more. The psychological cost is not as easily quantifiable but can be even more profound. The person with dementia loses control of many of the essential features of his life and personality, and loved ones lose a family member even as they continue to cope with the burdens of increasing dependence and unpredictability.

Causes and symptoms


Dementia usually is caused by degeneration in the cerebral cortex, the part of the brain responsible for thoughts, memories, actions, and personality. Death of brain cells in this region leads to the cognitive impairment that characterizes dementia.
The most common cause of dementia is AD, accounting for one-half to three-fourths of all cases. The brain of a person with AD becomes clogged with two abnormal structures called neurofibrillary tangles and senile plaques. Neurofibrillary tangles are twisted masses of protein fibers inside nerve cells (neurons). Senile plaques are composed of parts of neurons surrounding a group of proteins called beta-amyloid deposits. Why these structures develop is unknown. Current research indicates possible roles for inflammation, blood flow restriction, and molecular fragments known as free radicals.
Several genes have been associated with higher incidences of AD, although the exact role of these genes still is unclear. Discovered by researchers at Duke University in the early 1990s, potentially the most important genetic link to AD is on chromosome 19. A gene on this chromosome, called APOE (apolipoprotein E), codes for a protein involved in transporting lipids (fats) into neurons. Certain variations of this gene appear to increase the chance for developing AD and/or lower the age at which symptoms occur. Researchers believe that as many as seven other AD risk-factor genes exist. In 2007, scientists identified a possible risk factor in four new AD-related regions in the human genome. In these regions, one out of several hundred genes may be a risk factor. One gene called SORL 1 has drawn particular research attention. This gene is involved regulating the transport of certain proteins in the cell. As of 2009, the role SORL 1 in the development of AD remained under study.
Vascular dementia is estimated to cause from 5-30% of all dementias. It occurs from decrease in blood flow to the brain, most commonly due to a series of small strokes (multi-infarct dementia). Other cerebrovascular causes include vasculitis from syphilis, Lyme disease, or systemic lupus erythematosus (SLE); subdural hematoma; and subarachnoid hemorrhage. Because of the usually sudden nature of its cause, the symptoms of vascular dementia tend to begin more abruptly than those of Alzheimer's dementia. Symptoms may progress stepwise with the occurrence of new strokes. Unlike AD, the incidence of vascular dementia is lower after age 75.
Other conditions that may cause dementia include:
  • AIDS

  • Parkinson's disease

  • Lewy body disease

  • Pick's disease

  • Huntington's disease

  • Creutzfeldt-Jakob disease

  • brain tumor

  • hydrocephalus

  • head trauma

  • multiple sclerosis

  • prolonged abuse of alcohol or other drugs

  • vitamin deficiency: thiamin, niacin, or B12

  • hypothyroidism

  • hypercalcemia


Dementia is marked by a gradual impoverishment of thought and other mental activities. Losses eventually affect virtually every aspect of mental life. The slow progression of dementia is in contrast with delirium, which involves some of the same symptoms, but has a very rapid onset and fluctuating course with alteration in the level of consciousness. However, delirium may occur with dementia, especially since the person with dementia is more susceptible to the delirium-inducing effects of may types of drugs.
Symptoms of dementia include:
  • Memory losses. Memory loss usually is the first symptom noticed. It may begin with misplacing valuables such as a wallet or car keys, then progress to forgetting appointments and then to more substantive omissions such as forgetting where the car was parked or the route home. More profound losses follow, such as forgetting the names and faces of family members.

  • Impaired abstraction and planning. The person with dementia may lose the ability to perform familiar tasks, plan activities, and draw simple conclusions from facts.

  • Language and comprehension disturbances. The person with dementia may be unable to understand instructions or follow the logic of moderately complex sentences. Later, the individual may not understand his or her own sentences and have difficulty forming thoughts into words.

  • Poor judgment. The person with dementia may not recognize the consequences of his or her actions or be able to evaluate the appropriateness of behavior or level or risk. Behavior may become rude, overly friendly, or aggressive. Personal hygiene may be ignored.

  • Impaired orientation ability. The person may not be able to identify the time of day, even from obvious visual clues, or may not recognize his or her location, even if familiar. This disability may stem partly from losses of memory and partly from impaired abstraction.

  • Decreased attention and increased restlessness. This may cause the person with dementia to begin an activity and quickly lose interest and/or to wander frequently. Wandering may create significant safety problems when combined with disorientation and memory losses. For example, a person with dementia may begin to cook something on the stove, then become distracted and wander away while it is cooking.

  • Behavioral changes and psychosis. The person with dementia may lose interest in once-pleasurable activities and become more passive, depressed, or anxious. Delusions, suspicion, paranoia, and hallucinations may occur later in the disease. Sleep disturbances may occur, including insomnia and sleep interruptions.


Since dementia usually progresses slowly, diagnosing it in its early stages can be difficult. However, prompt intervention and treatment has been shown to help slow the effects of some dementias, so early diagnosis is important. Office visits over several months or more may be needed. Diagnosis begins with a thorough physical exam and complete medical history, usually including supplemental information from family members or caregivers. A family history of either AD or cerebrovascular disease may provide clues to the cause of symptoms. Simple tests of mental function, including word recall, object naming, and number-symbol matching, are used to track changes in the person's cognitive ability.
Depression is common in the elderly and can be mistaken for dementia; therefore, ruling out depression is part of the diagnosis. Distinguishing dementia from the mild normal cognitive decline of advanced age also is critical. The medical history should include a complete listing of drugs and dosages and being taken, since a number of drugs can cause dementia-like symptoms in the elderly.
Determining the cause of dementia may require a variety of medical tests, chosen to match the most likely etiology. Cerebrovascular disease, hydrocephalus, and tumors may be diagnosed with x rays, CT or MRI scans, and vascular imaging studies. Blood tests may reveal nutritional deficiencies or hormone imbalances.


Treatment of dementia begins with treatment of the underlying disease, where possible. The underlying causes of nutritional, hormonal, tumor-caused, and drug-related dementias may be reversible to some extent. Treatment for stroke-related dementia begins by minimizing the risk of further strokes through smoking cessation, aspirin therapy, and treatment of hypertension, for instance. Alzheimer's disease is, as of 2009, incurable; however, early diagnosis and prompt intervention can slow decline from AD and extend the period during which people the disease can maintain independent functioning. As of 2009, the United States Food and Drug Administration (FDA) had approved five prescription drugs for the treatment of AD symptoms. Four of these are used to treat mild to moderate AD. They are galantamine (Razadyne formerly known as Reminyl), rivastigmine (Exelon), donepezil (Aricept), and tacrine (Cognex). Tacrine, however, is rarely prescribed because of safety issues. These drugs all act by increasing the level of chemical signaling molecules (neurotransmitters) in the brain to help compensate for decreased communication ability among nerve cells. The fifth drug, memantine (Namenda), is used to treat moderate to severe AD. It acts by regulating a chemical in the brain called glutamate. None of these drugs cure or stop AD. In some individuals, they do slow the progression of symptoms by modestly increasing cognition and improving the individual's ability to perform normal activities of daily living.
Slowing or reversing dementia is an area of active research. Clinical trials of new drugs and therapies are ongoing. A list of current clinical trials that are enrolling volunteers can be found at Participation in a clinical trial is free to qualified volunteers.
Psychotic symptoms, including paranoia, delusions (false beliefs), and hallucinations (seeing things that are not there), may be treated with antipsychotic drugs such as haloperidol (Haldol), risperidone (Risperdal), quetiapine (Seroquel) and olanzapine (Zyprexa). Side effects of these drugs can be significant. Antianxiety drugs such as buspirone (BuSpar) may improve behavioral symptoms, especially agitation and anxiety. Depression is treated with antidepressants, usually selective serotonin reuptake inhibitors (SSRIs) such as sertraline (Zoloft) or paroxetine (Paxil). Sleep disturbances can also be treated with drugs, although many drugs for insomnia are recommended for short-term use only. In order to minimize side effects,medications generally should be administered cautiously and in the lowest possible effective doses to an individual with dementia. Caregivers generally must actively supervise the administration of all medications.

Alternative treatment

Antioxidants, which act to protect against oxidative damage caused by free radicals, have been shown to inhibit toxic effects of beta-amyloid in laboratory tissue cultures. Vitamin E, an antioxidant, is thought to delay AD onset. However, it is not yet clear whether this is due to the specific action of vitamin E on brain cells or to an increase in the overall health of those taking it. Research is being conducted to determine if vitamin E or other antioxidants may delay or prevent AD.
Ginkgo extract, derived from the leaves of the Ginkgo biloba tree, appeared to be one of the more promising alternative treatments for AD. A 1997 study of patients with dementia seemed to show that ginkgo extract could improve their symptoms, although the study was criticized for certain flaws in its method. Unfortunately, a large-scale, well-designed, follow-up study released in 2008 showed that Ginkgo extract neither prevented nor delayed AD.
Some alternative practitioners advise people with AD to take supplements of phosphatidylcholine, vitamin B12, gotu kola, ginseng, St. John's Wort, rosemary, saiko-keishi-to-shakuyaku (A Japanese herbal mixture), and folic acid. As of 2009, none of these alternative therapies met the safety and effectiveness standards of conventional Western medicine as a treatment for AD.

Supportive care

Care for a person with dementia can be difficult and complex. The individual with dementia must cope with functional and cognitive limitations, while family members or other caregivers assume increasing responsibility for the person's physical needs. In progressive dementias such as AD, the person may ultimately become completely dependent. Education of the patient and family early in the disease progression can help them anticipate and plan for inevitable changes.
Behavioral approaches may be used to reduce the frequency or severity of problem behaviors, such as aggression or socially inappropriate conduct. Problem behavior may be a reaction to frustration or overstimulation; understanding and modifying the situations that trigger it can be effective. Strategies may include breaking down complex tasks, such as dressing or feeding, into simpler steps, or reducing the amount of activity in the environment to avoid confusion and agitation. Pleasurable activities, such as crafts, games, and music, can provide therapeutic stimulation and improve mood.
Modifying the environment can increase safety and comfort while decreasing agitation. Home modifications for safety include removal or lock-up of hazards such as sharp knives, dangerous chemicals, and tools. Childproof latches or Dutch doors may be used to limit access as well. Lowering the hot water temperature to 120°F (48.9°C) or less reduces the risk of scalding. Bed rails and bathroom safety rails can be important safety measures, as well. Confusion may be reduced with simpler decorative schemes and presence of familiar objects. Covering or disguising doors (with a mural, for example) may reduce the tendency to wander. Positioning the bed in view of the bathroom can decrease incontinence.
Long-term institutional care may be needed for the person with dementia, as profound cognitive losses often precede death by a number of years. Early planning for the financial burden of nursing home care is critical. Useful information about financial planning for long-term care is available through the Alzheimer's Association (see resources).
Family members or others caring for a person with dementia often are subject to extreme stress, and may develop feelings of anger, resentment, guilt, and hopelessness, in addition to the sorrow they feel for their loved one and for themselves. Depression is an extremely common consequence of being a full-time caregiver for a person with dementia. Support groups can be an important way to deal with the stress of caregiving. The location and contact numbers for caregiver support groups are available from the Alzheimer's Association; they may also be available through a local social service agency or the patient's physician. Medical treatment for depression may be an important adjunct to group support.


The prognosis for dementia depends on the underlying disease. Alzheimer's disease is incurable and often fatal. When AD is not be the direct cause of death, the generally poorer health of a person with AD increases the risk of life-threatening infection, including pneumonia. In addition, other diseases common in old age such as cancer, stroke, and heart disease often have more severe consequences in a person with AD. Vascular dementia usually is progressive, with death from stroke, infection, or heart disease.


As of 2009, there was no way to distinguish between people who will develop dementia as they age and those who will not. There currently is no known way to prevent Alzheimer's disease, although several drugs may slow its progression. Various studies have reported that people over age 75 who actively participated in leisure activities such as playing board games, reading, dancing, and playing musical instruments were less likely to have dementia after five years than others their age. The risk of developing multi-infarct dementia may be reduced by reducing the risk of stroke.

Key Terms

Neurofibrillary tangles
Abnormal structures, composed of twisted masses of protein fibers within nerve cells, found in the brains of people with Alzheimer's disease.

One of a group of chemicals secreted by a nerve cell (neuron) to carry a chemical message to another nerve cell, often as a way of transmitting a nerve impulse. Examples of neurotransmitters include acetylcholine, dopamine, serotonin, and norepinephrine.

Senile plaques
Abnormal structures, composed of parts of nerve cells surrounding protein deposits, found in the brains of people with Alzheimer's disease.

For Your Information



  • Brumback, Roger A. Alzheimer's Disease: The Dignity Within: A Handbook for Caregivers, Family, and Friends. New York: Demos Medical Pub., 2005.

  • Petersen, Ronald. Mayo Clinic Guide to Alzheimer's Disease. Rochester, MN: Mayo Clinic, 2006.


  • "Dementia." MedlinePlus. February 17, 2009 [cited February 18, 2009].

  • Gerstein, Paul S. "Delirium, Dementia, and Amnesia." January 17, 2009 [cited February 18, 2009].

  • Sucholeiki, Roy and Richard J. Casselli. "Dementia: Overview of Pharmacotherapy." July 16, 2007 [cited February 18, 2009].


  • Alzheimer's Association. 225 N. Michigan Avenue, Floor 17, Chicago, IL 60611-7633. Telephone: (800) 272-3900; TTD: (866) 403-3973. 24-hour help line (800) 272-3900. Email:

  • Alzheimer's Disease Education and Referral (ADEAR) Center. P. O. Box 8250, Silver Spring MD 20907-8250. Telephone: (800) 438-4380. Fax: (301) 495-3334. Email:

  • National Institute on Aging. Building 31, Room 5C27, 31 Center Drive, MSC 2292 Bethesda, MD 20892. Telephone: (301) 496-1752. TTY: (800) 222-4225. Fax:(301) 496-1072.

Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


a general loss of cognitive abilities, including impairment of memory as well as one or more of the following: aphasia, apraxia, agnosia, or disturbed planning, organizing, and abstract thinking abilities. It does not include loss of intellectual functioning caused by clouding of consciousness (as in delirium), depression, or other functional mental disorder (pseudodementia). Causes include a large number of conditions, some reversible and some progressive, that result in widespread cerebral damage or dysfunction. The most common cause is Alzheimer's disease; others include cerebrovascular disease, central nervous system infection, brain trauma or tumors, vitamin deficiencies, anoxia, metabolic conditions, endocrine conditions, immune disorders, prion diseases, Wernicke-Korsakoff syndrome, normal-pressure hydrocephalus, Huntington's chorea, multiple sclerosis, and Parkinson's disease.
dementia of the Alzheimer type official name for alzheimer's disease.
Binswanger's dementia a progressive dementia of presenile onset due to demyelination of the subcortical white matter of the brain, with sclerotic changes in the blood vessels supplying it.
boxer's dementia a syndrome more serious than boxer's traumatic encephalopathy, the result of cumulative injuries to the brain in boxers; characterized by forgetfulness, slowness in thinking, dysarthric speech, and slow, uncertain movements, especially of the legs.
epileptic dementia a progressive mental and intellectual deterioration that occurs in a small fraction of cases of epilepsy; it is thought by some to be caused by degeneration of neurons resulting from circulatory disturbances during seizures.
multi-infarct dementia vascular d.
paralytic dementia (dementia paraly´tica) general paresis.
dementia prae´cox (obs.) schizophrenia.
presenile dementia name given to dementia of the Alzheimer type when it occurs in persons younger than age 65.
senile dementia name given to dementia of the Alzheimer type when it occurs in persons aged 65 or older.
substance-induced persisting dementia that resulting from exposure to or use or abuse of a substance, such as alcohol, sedatives, anxiolytics, anticonvulsants, lead, mercury, carbon monoxide, or organophosphate insecticides, but persisting long after exposure to the substance ends, usually with permanent and worsening deficits. Individual cases are named for the specific substance involved.
vascular dementia patchy deterioration of intellectual function resulting from damage by a significant cerebrovascular disorder.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


The loss, usually progressive, of cognitive and intellectual functions, without impairment of perception or consciousness; caused by a variety of disorders, (structural or degenerative) but most commonly associated with structural brain disease. Characterized by disorientation, impaired memory, judgment, and intellect, and a shallow labile affect.
Synonym(s): amentia (2)
[L. fr. de- priv. + mens, mind]
Farlex Partner Medical Dictionary © Farlex 2012


Loss of cognitive abilities, including memory, concentration, communication, planning, and abstract thinking, resulting from brain injury or from a disease such as Alzheimer's disease or Parkinson's disease. It is sometimes accompanied by emotional disturbance and personality changes.

de·men′tial adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Impairment of previously attained occupational or social functioning, due to development of acquired and persistent memory impairment associated with impairment of intellectual function in one or more of the following domains: language, visuospatial, skills, emotion or personality of cognition, in the presence of normal consciousness.

At age 60 to 69, 1% are demented; at age 90-95, 40% are demented.

Alzheimer’s, dementia with Lewy body formation, vascular dementia, frontotemporal dementia.

Rare causes of dementia
Degenerative disease, prion disease, metabolic/nutrition/toxic infections, hydrocephalus, neoplasia, head injury, demyelination.

Treatable causes of dementia
Endocrine and metabolic disease, thyroid or parathyroid disease, pituitary/adrenal dysfunction, hepatic encephalopathy, Wilson’s disease, chronic renal failure.
Cryptococcal meningitis, neurosyphilis.
Intracranial disorders
Hydrocephalic dementia, tumours.

SLE, periarteritis nodosa, temporal arteritis.

Vitamin deficiency
Thiamin, nicotinic acid, folic acid, vitamin B12.
Drugs and/or toxins, heart failure, “respiratory” encephalopathy, sarcoidosis, functional psychiatric disorders.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


Chronic brain failure, chronic brain syndrome, chronic organic brain syndrome, cortical and subcortical dementia, organic mental disorder, presbyophrenia, senility Neurology A general term for a diffuse irreversible condition of slow onset seen in older Pts, due to dysfunction of cerebral hemispheres; it is an end stage of mental deterioration, and is characterized by a loss of cognitive capacity, leading to ↓ social &/or occupational activity Prevalence Age-linked–affects ± 10.5% of those 80-85; 12.6-47.2% ≥ 85 Etiology 47% Vascular-type–potentially treatable; 44% Alzheimer's type Clinical ↓ mental ability, memory loss, often with emotional disturbances, personality changes Imaging MRI, PET, SPECT DiffDx Alzheimer's disease, multi-infarct–vascular dementia, Pick's disease, diffuse Lewy disease, Wernicke-Korsakoff syndrome, frontal lobe-type dementia, progressive supranuclear palsy, progressive subcortical gliosis, corticobasilar degeneration; other causes of dementia include alcohol, schizophrenia, subdural hematoma, normal pressure hydrocephalus, vitamin B12 deficiency and repeated trauma–'punch-drunk' syndrome, torture victims. See Dialysis dementia, Lewy body dementia, Multiinfarct dementia, Pseudodementia, Vascular dementia.
Dementia, treatable causes of
Endocrine & metabolic disease Thyroid or parathyroid disease, pituitary/adrenal dysfunction, hepatic encephalopathy, Wilson's disease, chronic renal failure
Infections Cryptococcal meningitis, neurosyphilis
Intracranial disorders Hydrocephalic dementia, tumors
Vasculitis SLE, periarteritis nodosa, temporal arteritis
Vitamin deficiency Thiamin, nicotinic acid, folic acid, vitamin B12
Others Drugs and/or toxins, heart failure, 'respiratory' encephalopathy, sarcoidosis, functional psychiatric disorders
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


The loss, usually progressive, of cognitive and intellectual functions, without impairment of perception or consciousness; caused by a variety of disorders including severe infections and toxins, but most commonly associated with structural brain disease. Characterized by disorientation, impaired memory, judgment, and intellect, and a shallow labile affect.
Synonym(s): amentia.
[L. fr. de- priv. + mens, mind]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


A syndrome of failing memory and progressive loss of intellectual power due to continuing degenerative disease of the brain. About half are believed to be due to ALZHEIMER'S DISEASE and about one third to small repeated STROKES. A small proportion are due to PRION DISEASE (spongiform encephalopathy). It has been shown that participation in leisure activities such as playing music, games and reading, are associated with a significantly lower risk of dementia, but it is not clear whether such activities reduce the risk.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


The loss, usually progressive, of cognitive and intellectual functions, without impairment of perception or consciousness; most commonly associated with structural brain disease.
[L. fr. de- priv. + mens, mind]
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about dementia

Q. how is dementia and alcoholism related

A. Alcohol can cause dementia through nutritional deficiencies (e.g. B1, or thiamine deficiency, causing Wernicke encephalopathy's_encephalopathy) and probably also through direct effect on the brain. It can also cause a rare neurological disorder called Marchiafava-Bignami disease that results from damage to the brain tissue in certain areas.

Further more alcohol may cause hepatic damage that can cause alteration in consciousness and dementia.

You can read more here:

Q. Is obesity a risk factor for Dementia?

A. The answer is YES. In fact, many of the risk factors for heart disease, such as high blood pressure, blood glucose levels, insulin resistance, and overweight, are also risk factors for dementia, in addition to genetic predisposition for the disease.

Q. discussing my father situation with the doctor My 82 years old dad has dementia, and currently lives with us at my home. For the last few weeks he's very nervous and sometimes yells and screams at us. I want to take him to the doctor and see if he can get any help, but I'm afraid that if I'll try to speak with doctor about this subject in front of my dad he'll take offense. What can I do? Thank you very much!

A. The answer above is a good suggestion. I would add to the letter a small warning about the way your father would react to a discussion of his behaviour so the doctor would know to discuss it carefully.

More discussions about dementia
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