Dementia is a neurological disorder that affects
your ability to think, speak, reason, remember and move. While Alzheimer's
disease is the most common cause of dementia, many other conditions also cause
these symptoms. Some of these disorders get worse with time and cannot be
cured. Other types can be treated and reversed.
The three most common forms of dementia are
Alzheimer's disease, vascular dementia and Lewy body dementia. Sometimes, a
person can have more than one of these problems at the same time. You can have dementia without having Alzheimer's disease but everyone with Alzheimer's disease will have dementia.
Alzheimer's disease involves a loss of nerve cells
in the areas of the brain vital to memory and other mental functions. This loss
is associated with the development of abnormal clumps and tangles of protein in
brain cells. The first sign of Alzheimer's disease is usually forgetfulness. As
the disease progresses, it affects language, reasoning and understanding.
Eventually, people with Alzheimer's lose the ability to care for themselves.
The precise cause of Alzheimer's disease is unknown, but risk increases with
age. Ten percent of the population over the age of 65 has Alzheimer's, while
nearly half of the population over 85 has the disease.
Another common form of dementia, vascular dementia
occurs when arteries feeding the brain become narrowed or blocked. The onset of
symptoms usually is abrupt, frequently occurring after a stroke. However, some
forms of vascular dementia progress slowly, making them difficult to
distinguish from Alzheimer's disease. Some people have Alzheimer's and vascular
dementia at the same time. Vascular dementia often causes problems with
thinking, language, walking, bladder control and vision. Preventing additional
strokes by treating underlying diseases, such as high blood pressure, may halt
the progression of vascular dementia.
Lewy body dementia: Has Alzheimer's-like and
Parkinson's-like features. In this form of dementia, abnormal round structures
- Lewy bodies - develop within cells of the midbrain, beneath the cerebral
hemispheres. Lewy body dementia shares characteristics with both Alzheimer's
disease and Parkinson's disease. Like Alzheimer's disease, it causes confusion
and impaired memory and judgment. And it often produces two distinctive
physical signs typical of Parkinson's disease - a shuffling gait and flexed
posture. Lewy body dementia can also cause hallucinations.
Lewy bodies contain a protein associated with
Parkinson's disease, and Lewy bodies often are found in the brains of people
who have Parkinson's disease or Alzheimer's disease. This suggests that the
three ailments are related, or that Lewy body dementia and Alzheimer's or
Parkinson's disease sometimes co-exist in the same person. Some people with
Lewy body dementia have experienced dramatic improvements in symptoms when
treated with Alzheimer's or Parkinson's medications.
Several less common brain disorders also can result
in dementia.
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Frontotemporal dementia. Because it affects the
lobes of the brain that are responsible for judgment and social behavior, frontotemporal
dementia can result in impolite and socially inappropriate behavior. Symptoms
of this form of dementia usually appear between the ages of 40 and 65. The
disease seems to run in families.
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Huntington's disease. Symptoms of this hereditary
disorder typically begin between the ages of 30 and 50, starting with mild
personality changes. As the disorder progresses, a person with Huntington's
develops involuntary jerky movements, muscle weakness and clumsiness. Dementia
commonly develops in the later stages of the disease.
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Parkinson's disease. People with Parkinson's
disease may experience stiffness of limbs, shaking at rest (tremor), speech
impairment and a shuffling gait. Some people with Parkinson's develop dementia
late in the disease.
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Creutzfeldt-Jakob disease. This extremely rare and
fatal brain disorder belongs to a family of human and animal diseases known as
the transmissible spongiform encephalopathies. A new variety of
Creutzfeldt-Jakob disease has emerged - particularly in Great Britain. It's believed
to be linked to the human consumption of beef from cattle with mad cow disease
(bovine spongiform encephalopathy).
Many other conditions, some reversible, can cause
dementia or dementia-like symptoms.
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Reactions to medications. Some medications have side
effects that mimic the symptoms of dementia. A single medicine may trigger such
a reaction in an older person or in someone whose liver fails to eliminate the
drug properly. Interactions among two or more drugs may lead to reversible
symptoms of dementia as well.
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Metabolic abnormalities. Decreased thyroid function
(hypothyroidism) can result in apathy, depression or dementia. Hypoglycemia, a
condition in which there isn't enough sugar in the bloodstream, can cause
confusion or personality changes. Pernicious anemia - an impaired ability to
absorb vitamin B-12 - also can cause personality changes.
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Nutritional deficiencies. Chronic alcoholism can
result in deficiencies of thiamin (vitamin B-1), which can seriously impair
mental abilities. Severe deficiency of vitamin B-6 may lead to pellagra, a
neurological illness with features of dementia. Dehydration also can cause
confusion that may resemble dementia.
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Emotional problems. The confusion, apathy and
forgetfulness associated with depression are sometimes mistaken for dementia,
particularly in older individuals.
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Infections. Meningitis and encephalitis, which are
infections of the brain or the membrane that covers it, can cause confusion,
memory loss or sudden dementia. Untreated syphilis can damage the brain and
cause dementia. People in the advanced stages of AIDS also may develop a form
of dementia.
Seek evaluation and treatment
Dementia isn't always due to Alzheimer's. Before
you conclude that a loved one's memory loss and confusion stem from an
irreversible disease process, get a thorough medical evaluation. Even if the
evaluation uncovers no underlying condition that, with treatment, can reverse
dementia, options may be available for easing its symptoms. Knowing the likely
cause of dementia, however, is the essential first step toward managing it.
