Reversible Dementias - Is It Alzheimers Or Another Dementia: Alzheimers

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Reversible dementias

Reversible dementias are often easier to diagnose than irreversible dementias because they are usually accompanied by other, obvious symptoms. In the following conditions or situations, however, dementia may be the primary, or even the only, symptom. Proper treatment may improve or even restore cognitive functioning.

Delirium

Delirium causes changes in mental functioning that can closely resemble dementia, but there are two important differences: speed of onset and level of consciousness. The mental changes in delirium develop quickly, often in a matter of hours or days, and consciousness is either clouded or fluctuates between drowsiness and alertness. In contrast, dementia evolves over months or years and doesn't affect the level of consciousness.

Delirium is considered a medical emergency, in part because it's often the main expression of a sudden, life-threatening illness. Elderly people are also susceptible to delirium after surgery. Alcohol withdrawal syndrome presents the classic picture of delirium. Similarly, delirium can occur from abrupt withdrawal from barbiturates or benzodiazepines, a group of anti-anxiety drugs that includes diazepam (Valium), chlordiazepoxide (Librium), and alprazolam (Xanax).

Toxic reactions to drugs

Medications are common culprits in mental decline. With aging, the liver becomes less efficient at metabolizing drugs, and the kidneys eliminate them from the body more slowly. As a result, drugs tend to accumulate in the body. Elderly people in poor health and those taking several different medications are especially vulnerable.

The list of drugs that can cause delirium and dementia-like symptoms is long. It includes antidepressants, antihistamines, anti-Parkinson drugs, anti-anxiety medications, cardiovascular drugs, anticonvulsants, corticosteroids, narcotics, and sedatives.

Depression

People sometimes manifest dementia-like symptoms — forgetfulness, disorientation, inattentiveness, and slowed responses — when they are depressed. This so-called pseudodementia can masquerade as the depression that often accompanies Alzheimer's disease, but there are subtle differences. In pseudodementia, the depressed mood begins before there is any mental decline. Typically, the person complains about memory loss or lack of concentration, looks sad or worried, and speaks in a flat, expressionless tone. In Alzheimer's-related depression, the mental decline comes first, and the person usually tries to conceal memory problems, rather than call attention to them.

Vitamin B₁₂ deficiency

Inadequate intake is rarely a cause of vitamin B₁₂ deficiency because this vitamin is plentiful in eggs, dairy products, meat, fish, and poultry, and it's efficiently stored in the liver. Instead, deficiency usually occurs because an individual can't absorb the vitamin from food. Untreated B₁₂ deficiency can have a variety of consequences, including pernicious anemia, a condition in which your body is unable to produce enough red blood cells (see Figure 5).

In older people, the first symptoms of pernicious anemia are often confusion, slowness, irritability, and apathy. Peripheral neuropathy — numbness and tingling in the feet and hands that grows progressively worse — is also a common symptom. However, B₁₂ injections, if started early, can remedy these symptoms.

Figure 5: B12 deficiency can cause dementia Dementia could be a symptom of pernicious anemia, a condition in which the bone marrow produces red blood cells that are larger than normal. There are also fewer cells than normal. Symptoms of pernicious anemia include yellowish skin, fatigue, shortness of breath, and headaches. Numbness or tingling in the hands and feet and trouble keeping balance are also common. Usually the B12 deficiency stems from an inability to absorb B12, not a lack of B12 in the diet.

Hydrocephalus

Hydrocephalus ("water on the brain") is an excess of cerebrospinal fluid around the brain. The fluid is secreted by the ventricles (cavities in the center of the brain). It circulates around the spinal cord and is absorbed by veins on the external surface of the brain. Congenital hydrocephalus is usually diagnosed shortly after birth, but normal-pressure hydrocephalus occurs in a small number of elderly people. This condition can result from head trauma, brain hemorrhage, or meningitis (inflammation of the membrane covering the brain), but most cases occur spontaneously without an obvious preceding illness.

In addition to developing dementia, people with this condition lose bladder control and walk in a slow, hesitant manner, as if their feet are stuck to the floor. A surgically implanted tube (shunt) that drains fluid from a cavity in the brain (the lateral ventricle) to the jugular vein or to the abdomen brings rapid improvement, provided treatment is started soon after the symptoms appear.

Tumors

Brain tumors can interfere with cognitive functioning and cause personality changes. Depending on their location, they can trigger other symptoms, such as headaches, seizures, or vomiting. But the first symptoms of slow-growing tumors frequently resemble dementia, especially in older people. Brain tumors may be malignant (cancerous) and therefore capable of invading surrounding tissue. Or they may be benign (self-contained).

Subdural hematomas

Hematomas are blood clots caused by bruising. When they are located in the subdural area, between the brain surface and the thin membrane that covers it (the dura), they can cause symptoms that mimic Alzheimer's disease. Such subdural hematomas can also be life-threatening, causing coma and death. Most subdural hematomas are caused by severe head trauma sustained in automobile crashes.

But elderly people sometimes develop subdural hematomas after a very minor (and, therefore, often forgotten) head injury. As blood oozes into a closed space, the hematoma enlarges and begins to interfere with brain function. Removing the clot within weeks of the injury may restore mental function. However, the symptoms often evolve so slowly that diagnosis is delayed for months.

Thyroid disease

An overproduction of thyroid hormones (hyperthyroidism) is commonly caused by Graves' disease, while an underproduction (hypothyroidism) usually results from Hashimoto's thyroiditis. Both disorders can cause dementia-like symptoms.

To diagnose hyperthyroidism, physicians use a simple blood test that measures levels of thyroid hormones. Surgically removing the thyroid or destroying it with radioactive iodine usually corrects the cognitive problems.

Hypothyroidism is diagnosed by measuring the level of thyroid-stimulating hormone circulating in the blood. Physicians usually recommend thyroid hormone replacement, but this treatment doesn't always reverse the dementia.

Alcoholism

Wernicke-Korsakoff syndrome, an irreversible state of confusion and amnesia in alcoholics, results from thiamine deficiency due to long-term malnutrition. But consuming excessive amounts of alcohol for a decade or more can also cause a dementia that resembles Alzheimer's disease. Memory, orientation, and attention are impaired, although verbal skills are not always severely affected. In this type of dementia, abstinence may partly restore mental functioning.

Last updated:	January 23, 2007