Alzheimer’s Disease

What is Alzheimer’s disease (AD)?

Alzheimer’s disease (AD) is an irreversible, progressive brain
disease that slowly destroys memory and thinking skills and, eventually,
the ability to carry out the simplest tasks of daily living. In most
people with AD, symptoms first appear after age 60.

AD is the most common cause of dementia among older people, but it is
not a normal part of aging. Dementia refers to a decline in cognitive
function that interferes with daily life and activities. AD starts in a
region of the brain that affects recent memory, then gradually spreads
to other parts of the brain. Although treatment can slow the progression
of AD and help manage its symptoms in some people, currently there is
no cure for this devastating disease.

AD is named after Dr. Alois Alzheimer, a German doctor. In 1906, Dr.
Alzheimer described changes in the brain tissue of a woman who had died
of an unusual mental illness. He found abnormal clumps (now called
amyloid plaques) and tangled bundles of fibers (now called
neurofibrillary tangles).

Today, these plaques and tangles in the brain are considered
hallmarks of AD. The third main feature of AD is the gradual loss of
connections between nerve cells (neurons) in the brain. This loss leads
to diminished cell function and cell death.

We don’t know what starts the AD process, but we do know that damage
to the brain begins as many as 10 to 20 years before any obvious signs
of forgetfulness appear.

As nerve cells die throughout the brain, affected regions begin to
shrink. By the final stage of AD, damage is widespread, and brain tissue
has shrunk significantly.

What causes AD?

Scientists don’t yet fully understand what causes AD, but it is clear
that it develops because of a complex series of events that take place
in the brain over a long period of time. It is likely that the causes
include genetic, environmental, and lifestyle factors. Because people
differ in their genetic make-up and lifestyle, the importance of these
factors for preventing or delaying AD differs from person to person.

Genetics play a role in some people with AD. A rare type of AD,
called early-onset AD, affects people ages 30 to 60. Some cases of
early-onset AD, called familial AD, are inherited. Familial AD is caused
by mutations (permanent changes) in three genes. Offspring in the same
generation have a 50-50 chance of developing familial AD if one of their
parents had it.

Most cases of AD are late-onset AD, which develops after age 60.
Although a specific gene has not been identified as the cause of
late-onset AD, genetic factors do appear to increase a person’s risk of
developing the disease. This increased risk is related to the
apoliprotein E (APOE) gene. The APOE gene has several forms. One of
them, APOE ε4, occurs in about 40 percent of all people who develop
late-onset AD. However, at least one-third of people with AD do not have
this form of the gene.

Four to seven other AD risk-factor genes may exist as well. One of
them, SORL1, was discovered in 2007. Large-scale genetic research
studies are looking for other risk-factor genes. For more information,
see the Alzheimer’s Disease Genetics Fact Sheet.

Research suggests that certain lifestyle factors, such as a
nutritious diet, exercise, social engagement, and mentally stimulating
pursuits, might help to reduce the risk of cognitive decline and AD.
Scientists are investigating associations between cognitive decline and
heart disease, high blood pressure, diabetes, and obesity. Understanding
these relationships and testing them in clinical trials will help us
understand whether reducing risk factors for these diseases may help
with AD as well.

Can AD be prevented?

We can’t control some risk factors for AD such as age and genetic
profile. But scientists are studying a number of other factors that
could make a difference. Only further research will reveal whether these
health, lifestyle, and environmental factors can help prevent AD. Some
of these factors are: physical activity, dietary factors such as
antioxidants and DHA, and damage to the vascular system.

What are the symptoms of Alzheimer’s Disease?

The course of AD is not the same in every person with the disease, but symptoms seem to develop over the same general stages.

Very early signs and symptoms

Memory problems are one of the first signs of AD. Some people with
mild AD have a condition called amnestic mild cognitive impairment
(MCI). People with MCI have more memory problems than normal for people
their age, but their symptoms are not as severe as those of people with
AD. More people with MCI go on to develop AD than people without MCI.

Mild AD

As AD progresses, memory loss continues and changes in other cognitive abilities appear. Symptoms in this stage can include:

  • getting lost
  • trouble handling money and paying bills
  • repeating questions
  • taking longer than before to complete normal daily tasks
  • poor judgment
  • losing things or misplacing them in odd places
  • mood and personality changes

In most people with AD, symptoms first appear after age 60. AD is often diagnosed at this stage.

Also see: The Seven Warning Signs of AD

Moderate AD

In moderate AD, damage occurs in areas of the brain that control
language, reasoning, sensory processing, and conscious thought. Symptoms
may include:

  • increased memory loss and confusion
  • problems recognizing family and friends
  • inability to learn new things
  • difficulty carrying out tasks that involve multiple steps (such as getting dressed)
  • problems coping with new situations
  • delusions and paranoia
  • impulsive behavior

Severe AD

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. Their symptoms often include:

  • inability to recognize oneself or family
  • inability to communicate
  • weight loss
  • seizures
  • skin infections
  • difficulty swallowing
  • groaning, moaning, or grunting
  • increased sleeping
  • lack of control of bowel and bladder

Also see: Understanding Stages and Symptoms of AD

For more information on Alzheimer’s Disease, please refer http://www.nia.nih.gov/Alzheimers/