Dementia is a general term that refers to a decline in cognitive function so extensive that it interferes with daily life and activities. This loss in the ability to think, remember, and reason is not a disease itself, but a group of symptoms that often accompanies a disease or condition.
Many conditions and diseases cause dementia. Two of the
most common causes of dementia in older people are AD
and vascular dementia, which is caused by a series of
strokes or changes in the brain’s blood supply.
Other conditions that cause memory loss or dementia
include:
• medication side effects
• chronic alcoholism
• certain tumors and infections in the brain
• blood clots in the brain
• vitamin B12 deficiency
• dehydration
• high fever
• some thyroid, kidney, or liver disorders
Many of these conditions are temporary and reversible, but they can be serious and should be treated by a doctor as soon as possible.
Emotional problems, such as stress, anxiety, or depression, can make a person more forgetful and can be mistaken for dementia. Someone may feel sad, lonely, worried, or bored when facing retirement or coping with the death of a spouse, relative, or friend. Adapting to these changes leaves some people feeling confused or forgetful. Supportive friends and family or professional help from a doctor or counselor can help older adults adjust to big changes.
What is mild cognitive impairment?
Mild cognitive impairment (MCI) is a condition in which
a person has memory problems greater than those expected
for his or her age. However, people with MCI do not have
the personality changes or cognitive problems that
characterize AD.
MCI has several types. The type most associated with
memory loss is called amnestic MCI. People with this
condition have more memory problems than normal for
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 those without MCI within a certain time frame.
However, not everyone who has MCI develops AD. Studies
are underway to learn why some people with MCI progress
to AD and others do not.
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.
How is AD diagnosed?
The only definite way to diagnose AD is with an autopsy,
which is an examination of the body done after a person
dies. However, doctors can determine fairly accurately
whether a person who is having memory problems has
“possible AD” (the symptoms may be due to another cause)
or “probable AD” (no other cause for the symptoms can be
found). To diagnose AD, doctors:
• ask questions about a person’s overall health, past
medical problems, ability to carry out daily activities,
and changes in behavior and personality
• conduct tests of memory, problem solving, attention,
counting, and language skills
• carry out medical tests, such as tests of blood,
urine, or spinal fluid
• perform brain scans, such as a computed tomography
(CT) scan or magnetic resonance imaging (MRI) test
These tests may be repeated to give doctors information
about how the person’s memory is changing over time.
Sometimes these tests help doctors find other possible
causes of the person's symptoms. For example, thyroid
problems, drug reactions, depression, brain tumors, and
blood-vessel disease in the brain can cause AD-like
symptoms. Some of these other conditions can be treated
successfully.
How is AD treated?
AD is a complex disease, and no single “magic bullet” is
likely to prevent or cure it. That’s why current
treatments focus on several different issues, including
helping people maintain mental function, managing
behavioral symptoms, and slowing AD.
AD research has developed to a point where scientists
can look beyond treating symptoms to think about
delaying or preventing AD by addressing the underlying
disease process. Scientists are looking at many possible
interventions, such as treatments for heart disease and
type 2 diabetes, immunization therapy, cognitive
training, changes in diet, and physical activity.
What drugs are currently available to treat AD?
No treatment has been proven to stop AD. The U.S. Food
and Drug Administration has approved four drugs to treat
AD. For people with mild or moderate AD, donepezil (Aricept®),
rivastigmine (Exelon®), or galantamine (Razadyne®) may
help maintain cognitive abilities and help control
certain behavioral symptoms for a few months to a few
years. Donepezil can be used for severe AD, too. Another
drug, memantine (Namenda®), is used to treat moderate to
severe AD. However, these drugs don’t stop or reverse AD
and appear to help patients only for months to a few
years.
These drugs work by regulating neurotransmitters, the
chemicals that transmit messages between neurons. They
may help maintain thinking, memory, and speaking skills
and may help with certain behavioral problems.
Other medicines may ease the behavioral symptoms of
AD—sleeplessness, agitation, wandering, anxiety, anger,
and depression. Treating these symptoms often makes
patients more comfortable and makes their care easier
for caregivers.
No published study directly compares the four approved
AD drugs. Because they work in a similar way, it is not
expected that switching from one of these drugs to
another will produce significantly different results.
However, an AD patient may respond better to one drug
than another.
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