Dementia: It's not always Alzheimer's

(MayoClinic.com) 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 can cause similar symptoms. Some of these disorders get worse with time and cannot be cured. Other types respond so well to treatment, their symptoms may even be reversed.

After Alzheimer's disease, the most common forms of dementia are vascular dementia and Lewy body dementia. Sometimes, a person can have more than one of these problems at the same time. Frontotemporal dementia is less common, but may be mistaken for Alzheimer's.

Vascular dementia
In vascular dementia, 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 so slowly that they are difficult to distinguish from Alzheimer's disease. Some people have both Alzheimer's and vascular dementia. 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
Lewy bodies are abnormal clumps of protein that have been found in the brains of people with Lewy body dementia, Alzheimer's disease and Parkinson's disease. This suggests that the three ailments are related, or that Lewy body dementia and Alzheimer's disease or Parkinson's disease sometimes coexist in the same person. Some people with Lewy body dementia have experienced improvements in symptoms when treated with Alzheimer's or Parkinson's medications.

Frontotemporal dementia
Because it affects the areas of the brain that are responsible for judgment and social behavior, frontotemporal dementia can result in socially inappropriate behavior. Symptoms of this form of dementia, which runs in families, usually appear between the ages of 40 and 65.

Several less common brain disorders also can result in dementia.

• 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.
• 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.
• 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).
• AIDS. People in the advanced stages of AIDS also may develop a form of dementia.

Many other conditions, some reversible, can cause dementia or dementia-like symptoms.

• 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 normally. Interactions among two or more drugs may lead to reversible symptoms of dementia as well.
• Metabolic abnormalities. Decreased thyroid function (hypothyroidism) can result in apathy or depression that mimics dementia. Hypoglycemia, a condition in which there isn't enough sugar in the bloodstream, can cause confusion or personality changes. Pernicious anemia caused by an inability to absorb vitamin B-12 also can cause cognitive changes.
• Nutritional deficiencies. Chronic alcoholism can result in deficiencies of thiamin (vitamin B-1), which can seriously impair mental abilities. Severe deficiency of niacin (vitamin B-3) may cause pellagra, a neurological illness with features of dementia. Dehydration also can cause confusion that may resemble dementia.
• Emotional problems. The confusion, apathy and forgetfulness associated with depression are sometimes mistaken for dementia, particularly in older individuals.
• 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.
• Normal-pressure hydrocephalus. If cerebrospinal fluid builds up in the ventricles of the brain, the brain tissue is compressed even though the fluid pressure remains normal. This may cause dementia. If this condition is identified in time, it may be treated by draining the excess fluid via a tube (shunt) leading into the abdomen.

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 appropriately.

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