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Dementia

Dementia

Reviewed by the Faculty of Harvard Medical School

Frequently Asked Questions


Is memory loss a normal part of growing old?
As you get older, your brain ages along with the rest of your body. As a natural part of the aging process, you will lose some of your mental ability. Because this change is generally gradual, pinpointing the exact age when mental ability declines is difficult. Researchers know that after age 50, episodes of memory loss occur more frequently.

However, this normal decline in mental function should not interfere with your ability to function in your daily life. In contrast, any drastic or sudden change in memory function may be indicative of an underlying disease. Your health-care provider should promptly assess any significant change in memory, personality, behavior, language or analytic skills.


How does memory change with age?
Age-related memory loss is a highly active area of research. There are many ways to assess memory, including written tests, verbal exercises and practical tests for specific tasks. What researchers know with certainty is that:

  • Age affects a variety of different memory tasks.


  • Not all memory tasks change with age in the same way.


  • As you age, you learn information more slowly. However, new research shows that if information is learned in the right way, an older person has the ability to remember just as efficiently as a younger person does.


  • Older people have more difficulty with short-term memory.


  • Laying down new memories is more difficult when an older person is asked to divide his or her attention or to reorganize material that has been presented.


Does a decline in memory indicate dementia?
Dementia is an umbrella term used to describe a decline in a number of brain activities that include memory loss. Some degree of age-related memory loss is normal. In people with dementia, the changes in memory are significant enough to affect the ability to function in daily life. In addition to memory loss, patients with dementia show changes in personality and behavior.


What causes dementia?
In some cases, dementia is caused by treatable conditions, such as:

  • Depression
  • Adverse reactions to medications
  • Infections, such as syphilis or fungal meningitis
  • Metabolic conditions, such as deficiencies in vitamin B12, folate or thyroid hormone

In these cases, dementia may be partially or entirely reversed if diagnosed and treated early. Your health-care provider should rule out these causes first.

However, most causes of dementia are not curable. This type of irreversible dementia commonly results from the degeneration or interruption of brain neurons (the connections in the brain). This can have a variety of causes:

  • Alzheimer's disease (in 40 percent to 45 percent of cases)
  • Multi-infarct or vascular dementia (in 20 percent of cases)
  • Lewy body disease (in 20 percent of cases)
  • Creutzfeldt-Jakob disease
  • Traumatic head injury
  • AIDS
  • Alcohol in high amounts over many years
  • Huntington's disease
  • Pick's disease (a degenerative disease of the brain)
  • Brain abscess
  • Multiple sclerosis
  • More than 50 other rare degenerative conditions


What is Alzheimer's disease?
Alzheimer's disease is a progressive, degenerative brain disease. It initially affects memory, but as the disease progresses, it involves many other brain functions. It eventually leads to physical illness and, ultimately, to death. Characteristic changes occur in the brains of people with Alzheimer's disease. These changes cannot be detected by current laboratory tests. With time, tests may become available to diagnose the disease and to determine whether or not a person will develop it.


Can I inherit Alzheimer's disease?
A few patients with Alzheimer's disease (about 3 percent) have a genetic abnormality that is believed to be the cause of their disease. This abnormality is in the chromosomes — the genetic material that you inherit from your parents. A specific abnormality in one of these chromosomes will result in Alzheimer's disease. Researchers refer to this as autosomal-dominant inheritance because a defect in just one chromosome can result in the disease, which is passed from one generation to the next. This is a rare form of Alzheimer's disease that affects young patients. It is best to think of Alzheimer's as a disease of the elderly.


What treatment is available for Alzheimer's disease?
Alzheimer's disease affects a system of signal transmissions in the brain that is known as the cholinergic system. Medications have been developed to restore cholinergic function. There are four medications approved by the U.S. Food and Drug Administration (FDA) for the treatment of Alzheimer's disease that act on the cholinergic system. These are:

Drug
Trade name
Donepezil
Aricept
Galantamine
Reminyl
Rivastigmine
Exelon
Tacrine
Cognex

Although these medications do not offer a cure, they can improve the symptoms of mild to moderate dementia.

In October 2003, a new medication was approved by the FDA for the treatment of Alzheimer's disease. This is memantine (Namenda).

Namenda works in an entirely different way than the previously available medications. It has been approved for the treatment of moderate to severe Alzheimer's disease. In studies of patients with moderate to severe Alzheimer's disease, those who took Nameda by itself showed a slower decline in mental function when compared with those who took placebo (a sugar pill). In a separate study, those who took Namenda in combination with donepezil (Aricept) vs. donepezil alone, also showed a slower decline in mental function.

New medications are being developed, and initial research results appear promising.

Studies are now being conducted to test the efficacy of nonsteroidal anti-inflammatory drugs, vitamin E, estrogen and the Chinese herb Ginkgo biloba. Studies show that arthritis patients who take NSAIDs and women who take replacemtn estrogen have a lower incidence of Alzheimer's disease than does the general population. Ginkgo biloba mildly improves short-term memory loss, headache and depression.

There are other medications that target the buildup of plaque on the brain. These medications are being studied, and resarchers hope to develop a vaccine.

Treatment of the complications of Alzheimer's disease, including behavioral disorders, depression and sleep disturbances, requires careful assessment of social and environmental issues and the exclusion of other medical causes. Threatment should initially involve lifestyle changes. Should this fail, medications can then be considered.



Last updated August 24, 2004



Approximately 15 percent of people older than 65 are thought to have dementia.
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