What is Dementia?

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What is Dementia?

Dementia is the term used for loss of intellectual and social function to the extent that this interferes with the person's daily life. For centuries, people called it "senility" and considered it an inevitable part of aging. It is now known that dementia is not a normal part of the aging process and that it is caused by some underlying condition.

Dementing illnesses can affect adults of any age. Although it is not a normal part of ageing, dementia is most likely to occur in later years.

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), dementia can be diagnosed if the patient has impaired memory and at least one of the following cognitive deficits:[1]

Aphasia - Difficulty expressing oneself in speech or writing or difficulty in understanding either.
Apraxia - Impaired ability to carry out motor activities despite intact motor function.
Agnosia - Failure to recognize or identify objects despite intact sensory function.
A decline in executive functioning - That is, problems with planning, organizing, sequencing, and abstracting.

To be diagnosed as dementia, these cognitive deficits must significantly affect a person's social or occupational functioning and represent a significant decline from previous levels of functioning. And the deficits must not result exclusively from delirium. Delirium comes on suddenly, and in addition to memory impairment, is characterized by attention deficits, impaired consciousness, and perceptual problems like hallucinations or delusions.

Symptoms of dementia vary in severity, order of appearance and with the type of dementia. But all dementias involve some impairment of memory, thinking, reasoning and language. Personality changes and abnormal behavior may also occur as dementia progresses.

Reference:
1. American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders, DSM-IV (4th ed.). Washington, DC: Author.

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What are the Most Common Forms of Dementia?

There are many causes of dementia so it is important to consult a doctor who is experienced in diagnosing these disorders as soon as possible.

Alzheimer's Disease

Alzheimer's Disease is the most common of the dementias and accounts for about 70 percent of all cases.

Of the diseases that produce dementia, Alzheimer's is the most common. The disease was named after Alois Alzheimer, a German physician. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. He found abnormal clumps (plaques) and tangled bundles of fibers (tangles). Other changes in the brains of people with Alzheimer's disease include a loss of nerve cells in the areas of the brain vital to memory and other mental functions, and lowered levels of chemicals in the brain that carry complex messages back and forth between billions of nerve cells important to thinking and memory.

The first sign of Alzheimer's disease may be mild forgetfulness. The disease progresses to affect language and conversation, the ability to do routine tasks, simple reasoning, understanding, reading or writing. Eventually, people with Alzheimer's disease may become anxious or aggressive, and may even wander from home. As the disease gradually progresses, the changes become more dramatic until, in the last stages, the person may need constant nursing care.


Parkinson's Disease

Parkinson's Disease (PD) is a progressive disorder of the central nervous system, characterised by tremors, stiffness in limbs and joints, speech impediments and difficulty in initiating physical movements. As many as 30 percent to 40 percent of people with Parkinson's disease, a progressive, neurodegenerative disease, will develop dementia during the later course of the disease. It is thought that most older people with Parkinson's disease also have dementia. Parkinson's disease is characterized by stiffness of the limbs, shaking at rest (tremor), speech impediments, and shuffling gait. Conversely, some Alzheimer patients develop symptoms of Parkinson's disease. Medication may improve physical symptoms for a time, but these may also WORSEN dementia.


Lewy Body Dementia

Advances in molecular biology and diagnostic techniques in the past 5 years have helped identify a correlation between Parkinson's disease and dementia and some features of Alzheimer's disease. The finding has caused some researchers to suggest that the second most common cause of dementia may be what is called Lewy body disease or dementia.

Lewy bodies are protein deposits found in deteriorating nerve cells. They often appear in damaged regions deep within the brains of people with Parkinson's disease. When Lewy bodies are found more diffusely dispersed throughout the brain, a dementia results with symptoms similar to those of Alzheimer's disease.

There are differences, however, between Lewy body dementia and Alzheimer's disease. Lewy body dementia progresses differently and includes fluctuations in cognitive impairment, including episodes of confusion. People with Lewy body dementia also experience hallucinations, which make it difficult to discern what is real or unreal. Although the early effects of Lewy body dementia tend to fluctuate, ultimately the impairments are severe and constant.

At autopsy, the brains of individuals with Lewy body dementia are speckled with Lewy bodies, just as they are in people with Parkinson's disease. In addition, Lewy bodies are found in the cortex, often along with the plaques (but not tangles) found in Alzheimer's disease. Lewy body dementia, like Alzheimer's disease, is irreversible.

What is significant is that the genetic changes that trigger these neurodegenerative conditions may have more in common than previously known. Research offers the best hope for pinpointing these and other types of dementias and refining treatments.

There is disagreement, however, over whether diffuse Lewy body dementia is a distinct illness or a variant of Alzheimer's or Parkinson's disease. Dementia is often mild at the outset and can be extremely variable from day to day. Symptoms such as delusions, extreme confusion, hallucinations, falls and Parkinson's-type tremors are common. People with Lewy body dementia are very sensitive to side effects of neuroleptic drugs (antipsychotics, e.g., Melleril and Serenace). There is no treatment at present.


Vascular Dementia

Vascular Dementia is the second most common cause of dementia. It is a term for dementia associated with problems in the circulation of blood to the brain cerebrovascular disease). It can result from several cerebral vascular diseases and occurs more often in men, especially those with hypertension or other cardiovascular risk factors.

One clue to its existence: Symptoms usually come on shortly after an MI or other cardio- or cerebrovascular event.[2] And, rather than a gradual mental decline, symptoms occur in a step-wise fashion with significant mental deterioration after each event. You're also likely to see neurological evidence of cerebrovascular disease, including dysphagia, paralysis of a limb, or headaches.

A CT and an MRI can help differentiate multi-infarct dementia from Alzheimer's because they may reveal vascular lesions in the cerebral cortex and subcortical areas.

If the diagnostic workup reveals vascular dementia, treatment consists of managing the risk factors that contribute to cerebrovascular disease, including hypertension, hyperlipidemia, diabetes, alcohol dependence, and smoking.[3] Occasionally, such treatment can slow, or even stop, progression of this particular dementia.[4] There is no treatment as yet to reverse the effects of vascular dementia, though drugs may be used to control high blood pressure (hypertension) which is known to be a risk factor.

Multi-Infarct Dementia (MID) is the most common kind of vascular dementia and is the result of many small strokes (infarcts) or from the narrowing and blockage of the arteries that supply blood to the brain. These strokes may damage any area of the brain responsible for a specific function. If there is one in a strategic area, dementia may result. People with this type of dementia often exhibit a stepwise deterioration of cognition function and ability. Paralysis, difficulty with language and vision loss are common. Vascular dementias are generally considered irreversible and the symptoms may appear similar to those called by Alzheimer's disease.

Subcortical Vascular Dementia (Binswanger's disease) is another slowly evolving type of dementia but the blood vessels affected are deep inside the brain (in the subcortex). Symptoms include slowness and lethargy and emotional ups and downs.


Frontal Lobe or Fronto-Temporal Dementias:

Pick's disease

Pick's disease is a rare brain disorder characterized by disturbances in behavior, personality and eventually memory. The disease is relentless in its progression, which may ultimately include language impairment, erratic behavior, and dementia. Because of the strange behavior associated with Pick's, people are often seen first by psychiatrists. Like Alzheimer's disease, a diagnosis is usually confirmed at autopsy.

With this condition, you'll see a slowly progressing dementia that's characterized by aphasia, apraxia, and amnesia. Onset occurs between the ages of 50 and 65.[7] Although we don't know what causes the disease, we do know that many of its symptoms result from the loss of neurons in the frontal or temporal lobes and the presence of unique formations - called Pick's bodies - in nerve cells.

An inherited dominant disorder that accounts for only 5% of all irreversible dementias,[3] Pick's disease is especially common in first-degree relations of those who already have the condition. Among the symptoms that sometimes distinguish it from Alzheimer's: marked apathy, psychomotor slowing, grasping and sucking reflexes, and hypersexuality.

On the surface, many forms of dementia look the same. But looking beneath the surface can help you pinpoint the exact cause of your patients' symptoms. And that's really the only way they're going to get the type of therapy that addresses their specific needs.

The frontal lobe dementias cause less than 10% of all dementias. As the name suggests, these disorders affect mainly the frontal and temporal lobes of the brain and usually begins between 40 to 65 years of age.

Disturbances of personality, behaviour (particularly lack of inhibitions) and language may precede and initially be more severe than memory defects.

The causes of Frontal Lobe dementia and Pick's disease are not yet known, but in a minority of cases they run in families.


Huntington's disease

Huntington's Disease is a progressive inherited degenerative brain disease that causes progressive degeneration of the basal ganglia and cerebral cortex, which affects the mind and body. It stems from a disorder within the brain which causes certain nerve cells to waste away. It usually appears between the ages of 30 and 50 and is characterised by intellectual decline and irregular, involuntary movement of the limbs or facial muscles. The characteristic rapid, jerky muscle spasms of the arms and legs help set it apart from Alzheimer's. Other signs to look for include personality change, memory disturbance, slurred speech, impaired judgement, progressive rigidity, akinesia, irritability, moodiness, and antisocial or psychotic behavior.[5] Diagnosis includes an evaluation of family medical history and CAT brain scanning. CT scanning shows cerebral atrophy and atrophy of the caudate nucleus. There is no treatment available to stop the progression of the disease, but medication can control movement disorders and psychiatric symptoms. Drugs that block dopamine receptors, like phenothiazines or haloperidol (Haldol), may help control the akinesia and behavioral problems; the latter may also respond to clonazepam (Klonopin). Dementia may develop in the later stages of the disease. Huntington's is known to be caused by a genetic disorder, and the gene that causes this disease has been identified.


Alcohol

Alcohol, if taken in excess, leads to irreversible brain damage. This is particularly so if it is also associated with poor diet, blackouts and frequent falls. The most vulnerable parts of the brain are those used for memory, higher cognitive tasks such as planning, organising and judgement, social skills and balance. If drinking ceases, there can be some improvement. Thiamine, a vitamin, is important to limit some of the toxic effects of alcohol, and is an important supplement for heavy drinkers.


Structural Brain Problems

Head Injury, if severe, can produce permanent change in a person's ability to think and in their behaviour and personality. Usually this follows only if a person has been unconscious for a long time.

Benign Tumour or hydrocephalus can cause dementia. Hydrocephalus does this by a build-up of the pressure of fluid inside the brain cavities. Often there is a history of meningitis, bleeding inside the head or head trauma and/or headache. Symptoms include shuffling walk and incontinence of urine, as well as slowing of thinking. If detected early, it can sometimes be treated by removing the tumour or insertion of a shunt to drain the fluid from the brain and so relieve the pressure. Unfortunately, this treatment does not always work to reverse the dementia.


Infection Related Dementias

Infection can cause some forms of dementia. The most common of these in the past was syphilis. Today, many people in the later stages of AIDS develop HIV related dementia. Symptoms can include apathy, vagueness, confusion, difficulty in concentrating, forgetfulness, withdrawal and flattened emotions. However, aspects of the person's original personality will usually remain intact to the end.

It's generally easy to distinguish a patient with full-blown AIDS dementia from one with another form of dementia because the former is usually younger, and the majority of these patients already have the distinctive signs and symptoms of AIDS. A greater challenge is telling the difference between AIDS dementia, which may include depressive symptoms, and the "garden variety" depression that many AIDS patients suffer from.

AIDS dementia is often accompanied by the appearance of MRI abnormalities and is characterized by memory loss, poor judgment, and the inability to plan and reason. Patients may also present with a deterioration in handwriting and diminished motor speed.

Symptoms may wax and wane, with patients alternating between lucidity and confusion over a 24-hour period.[5] Although we do not completely understand what causes AIDS dementia, a number of patients improve somewhat with zidovudine (Retrovir).


Creutzfeldt-Jakob Disease

Despite recent publicity about Mad Cow disease, this is still an extremely rare, fatal brain disorder caused by a mutated biological particle of protein called a "prion. " Early symptoms include failing memory, changes of behaviour and a lack of coordination. As the disease progresses, usually very rapidly, mental deterioration becomes pronounced, involuntary movements (muscle jerks) appear, and the patient may become blind, develop weakness in the arms or legs and ultimately lapse into a coma.

The prion can be transmitted by eating tainted meat. Prion variants affect different parts of the human brain. It is possible that prions may be responsible for other brain-connected diseases in humans.


Dementia-Like Symptoms which are Treatable and/or Potentially Reversible Dementias

There are potentially reversible conditions that may cause or mimic dementia. Among these conditions are brain tumors, head injuries, metabolic changes, thyroid problems and nutritional deficiencies (vitamin B12 being the most common). Toxins, including chronic alcohol abuse, drugs or medication, may cause confusion, cognitive decline and dementia. If detected and treated early, these dementias can be reversed or their progress halted.

Normal pressure hydrocephalus is an uncommon disorder characterized by an obstruction in the flow of cerebrospinal fluid, which causes a buildup of this fluid on the brain. Symptoms of the condition include dementia, urinary incontinence and difficulty in walking. The condition may be caused by meningitis, encephalitis or head injury. If diagnosed early in the disease, normal-pressure hydrocephalus is treatable by surgery in which a shunt is inserted to divert the fluid away from the brain.

Depression is often mistaken for dementia in older adults, and conversely, dementia for depression. Symptoms of depression include sadness, difficulty thinking and concentrating, feelings of despair and inactivity. When the depression is severe, poor concentration and attention may occur. When dementia and depression do occur together (which may be in as many as 40 percent of dementia cases), the intellectual deterioration may be more extreme. Depression, alone or in combination with dementia, is treatable. The challenge is to make an early assessment that pinpoints the condition.

Delirium, a state of temporary but acute mental confusion, is common in older people who have a short-term illness such as lung or heart disease, long-term infections, poor nutrition, medication interactions or hormone disorders. Emergency treatment of delirium is vital since a serious medical illness such as bacterial meningitis may be the underlying cause. Symptoms of delirium are sometimes confused with dementia. However, a person who exhibits sudden cognitive impairment, disorientation or loss of consciousness is likely to have delirium rather than dementia.

Serious forgetfulness and some other dementia-like symptoms sometimes are caused by a condition which can be cured. When such a condition is treated appropriately, the memory improves. Therefore, it is important for anyone with dementia-like behaviour to seek a thorough assessment to find the cause. Loss of memory in dementia is more than becoming a little forgetful. It is persistent and progressive, not just occasional.

Some medical problems can make any dementia appear worse than it need be. These include infections, painful disorders and uncontrolled chronic disease such as heart, liver or kidney failure. Even constipation makes dementia worse.

Remember - age presents a risk factor, but is not the cause of dementia.

References:
1. Abrams, W., Beers, M., et al. (Eds.). (1995). Merck manual of geriatrics (2nd ed.). Whitehouse Station, NJ: Merck Research Laboratories.
2. Greenfield, S. (Ed.). (1996). The human mind explained: An owner's guide to the mysteries of the mind. New York: Henry Holt and Company.
3. Adams, R., & Maurice, V. (1994). Principles of neurology (5th ed.). New York: McGraw-Hill.
4. Caine, E. D., Grossman, H., & Lyness, J. M. (1995). Delirium, dementia, and amnestic and other cognitive disorders and mental disorders due to a general medical condition. In H. I. Kaplan & B. J. Sadock. (Eds.), Comprehensive textbook of psychiatry (Vol. 1), (6th ed.). Baltimore: Williams and Wilkins.
5. Tierney, L., McPhee, S., & Papadakis, M. (1998). Current medical diagnosis and treatment (37th ed.). Stamford, CT: Appleton & Lange.
6. Beal, M. F., Richardson, E. P., & Martin, J. B. (1995). Alzheimer's disease and other dementias. In K. J. Isselbacher, E. Braunwald, et al. (Eds.), Harrison's principles of internal medicine (13th ed.). New York: McGraw-Hill.
7. Kaplan, H. I., Sadock, B., & Grebb, J. (1994). Synopsis of psychiatry: Behavioral sciences, clinical psychiatry (7th ed). Baltimore: Williams and Wilkins.

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Levels of Impairment and Symptoms of Dementia

Mild Impairment

Recent memory loss at times
Mild difficulty with verbal expression
Decreased concentration
Slowed learning and reactions
Seeks and prefers the familiar; avoids the unfamiliar
Difficulty with planning and decision making
Some errors in judgement and calculation
Lack of spontaneity and lessening of initiative

Moderate Impairment

Chronic, recent memory loss
Increased inability to comprehend and carry on a conversation
Difficulty in writing and using objects correctly
Visual-spatial perception problems
Possible delutions, hallucinations and agitation
Repetitive actions
May get lost at times, even inside the home
Needs reminder to perform activities of daily living

Severe Impairment

Inability to carry on any conversation
Difficulty with wayfinding
Misidentifies persons or objects
Bladder incontinence
Unsteady gait
Needs help with most or all activities of daily living

Terminal

Mute or few incoherent words
Bedridden or wheelchair bound
Minimally connected to surroundings
Little spontaneous movement
Difficulty in eating and swallowing
Seizures, muscle twitching
Cachexia
Requires total care


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Document last modified: 01/19/08 06:40:35 PM