About Alzheimer's Disease

On this page:

What is Alzheimer's disease?

What is dementia?

What is multi-infarct dementia (MID)?

What is mild cognitive impairment (MCI)


What is Alzheimer's Disease?

Alzheimer's disease (AD) is the most common form of dementia among older people, but it is not a normal part of aging. Alzheimer's disease usually begins after age 60, and risk goes up with age. While younger people also may get AD, it is much less common. About 5% of men and women ages 65 to 74 have AD, and nearly half of those age 85 and older may have the disease.

AD is characterized by a gradual loss of memory, decline in the ability to perform routine tasks, disorientation, difficulty in learning, loss of language skills, impaired judgment and ability to plan, and personality changes. Although scientists are learning more every day, right now they still do not know what causes AD, and there is no cure.

Alzheimer's disease develops slowly and causes changes in the brain long before there are obvious changes in a person's memory, thinking, use of words, or behavior. The course the disease takes and how fast changes occur vary from person to person, but symptoms seem to develop over the same general stages.

AD begins slowly, starting with mild memory problems and ending with severe brain damage. At first, the only symptom may be forgetfulness, which can be confused with age-related memory change. In moderate AD, damage occurs in areas of the brain that control language, reasoning, sensory processing, and conscious thought. People with severe AD cannot communicate and are completely dependent on others for their care. Near the end, the person with AD may be in bed most or all of the time. On average, AD patients live from 8 to 10 years after they are diagnosed, though the disease can last for as many as 20 years.

What is Dementia?

The term "dementia" describes a group of symptoms that are caused by changes in brain function that seriously affect a person's ability to carry out daily activities. Dementia symptoms may include asking the same questions repeatedly; becoming lost in familiar places; being unable to follow directions; getting disoriented about time, people, and places; and neglecting personal safety, hygiene, and nutrition. People with dementia lose their abilities at different rates.

Dementia can be caused by many conditions. Some conditions that cause dementia can be reversed, and others cannot. The two most common forms of dementia in older people are Alzheimer's disease and multi-infarct dementia (sometimes called vascular dementia or post-stroke dementia). These types of dementia are irreversible, which means they cannot be cured.

Reversible conditions with symptoms of dementia can include:

  • high fever
  • dehydration
  • vitamin deficiency and poor nutrition
  • bad reactions to medicines
  • problems with the thyroid gland
  • a minor head injury

Medical conditions like these can be serious and should be treated by a doctor as soon as possible.

Sometimes older people have emotional problems that can be mistaken for dementia. Feeling sad, lonely, worried, or bored may be more common for older people facing retirement or coping with the death of a spouse, relative, or friend. Adapting to these changes leaves some people feeling confused or forgetful. Emotional problems can be eased by supportive friends and family, or by professional help from a doctor or counselor.

What is Multi-Infarct Dementia (MID)?

In multi-infarct dementia, a series of small strokes or changes in the brain's blood supply may result in the death of brain tissue. The location in the brain where the small strokes occur determines the seriousness of the problem and the symptoms that arise. Symptoms that begin suddenly may be a sign of this kind of dementia. People with multi-infarct dementia are likely to show signs of improvement or remain stable for long periods of time, then quickly develop new symptoms if more strokes occur. In many people with multi-infarct dementia, high blood pressure is to blame. One of the most important reasons for controlling high blood pressure is to prevent strokes.

What is Mild Cognitive Impairment (MCI)?

During the past several years, scientists have focused on a type of memory change called mild cognitive impairment (MCI). MCI is different from both AD and normal age-related memory change. People with MCI have ongoing memory problems but do not have other losses like confusion, attention problems, and difficulty with language. It is estimated that about 22 percent of individuals over the age of 70 have MCI. Each year, about 12 percent of individuals with MCI go on to develop dementia.