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Alzheimer's Disease in Down Syndrome (cont.)

What is the link between down syndrome and Alzheimer's disease?

The reason Alzheimer's disease is more common in people with Down syndrome is not completely known. Alzheimer's disease is associated with increased production of a compound called amyloid beta in the brain. Amyloid beta accumulates and causes loss of brain cells called neurons. Exactly how neuron loss occurs is not well understood. The higher risk for Alzheimer's disease in people with Down syndrome may be related to the extra copy of chromosome 21 (which causes Down syndrome) because it leads to increased production of amyloid beta.

The age when symptoms of Alzheimer's disease actually develop may be related to a person's mental capacity (cognitive reserve) or some anatomic characteristics of the brain. That means people with greater brain weight, more brain cells (neurons), and more education may not have symptoms of Alzheimer's disease as early as people with less cognitive reserve. People with Down syndrome may develop symptoms of Alzheimer's disease earlier in life than other people because of their increased production of amyloid beta and their smaller cognitive reserve.

What are the symptoms of Alzheimer's Disease in people with Down syndrome?

In people with Down syndrome, the first symptoms usually develop at age 50 years, and the disease is usually diagnosed by age 52 years. Death occurs at an average age of 60.11 years. The time from the first symptoms of Alzheimer's disease to death is usually about 9 years.

Symptoms of the early stage of Alzheimer's disease

  • The main symptoms are confusion, disorientation, and wandering. These early signs are not usually recognized and are commonly misdiagnosed.
  • Behavioral changes also occur.
    • Early behavior changes that are truly related to Alzheimer's disease are often seen as an exaggeration of the person's normal traits. For example, the person may refuse to follow certain directions or to do chores because of Alzheimer's-related mental changes, but this refusal may be perceived as stubbornness.
    • Because these early changes are hard to recognize, only those familiar with the individual notice these changes. Changes can include change in daily routine, change in sleeping or eating habits, inability to make decisions about clothing, getting lost in familiar environments, and inability to remember the names of familiar people.
    • Another early sign of Alzheimer's disease in highly functional individuals with Down syndrome is the inability to perform job duties.
  • Visual problems can develop in the early stages of Alzheimer's disease. Because of these visual problems combined with the cognitive and memory deficits, individuals with Down syndrome:
    • can get lost in familiar environments,
    • may not be able to perform certain activities,
    • may have accidents and falls, and
    • may have difficulty learning new tasks.
  • Learning is usually impaired, but it is difficult to demonstrate in people with greater disability related to Down syndrome.
  • Other early signs include loss of language and other communication skills, impairment of social skills, and progressive loss of "activities of daily living" (ADL) (for example, personal hygiene, dining skills, bathroom skills).

Symptoms of the middle stage of Alzheimer's disease

  • ADL markedly deteriorate. The patient may depend totally on others for activities such as dressing, eating, walking, and toilet needs.
  • Communication is reduced.
  • Any behavioral problems are usually exaggerated, and psychotic behavior may develop. Social activities are reduced to a minimum.

Symptoms of the advanced stage of Alzheimer's disease

  • People with Down syndrome and advanced Alzheimer's disease seem almost to be in a coma.
  • They totally depend on others and interact minimally with the environment.

Physical symptoms of Alzheimer's disease are similar to those in people without Down syndrome and include the following:

  • Motor disorders may be observed in the early stage but become obvious in the middle stage of the disease. Walking becomes difficult, and in the advanced stage, the person is confined to bed and has almost no voluntary movements.
  • Eating disorders may be observed at the beginning of the disease but are more obvious in the middle stage. The person has problems swallowing and frequently chokes.
  • Epileptic seizures can develop.

Picture of a brain with Alzheimer's disease.
Picture of a brain with Alzheimer's disease. Click to view larger image.

Medically Reviewed by a Doctor on 6/23/2016
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