Dementia
is a loss of brain function that occurs with certain diseases. Alzheimer's
disease (AD), is one form of dementia that gradually gets worse over time. It
affects memory, thinking, and behavior.
Memory
impairment, as well as problems with language, decision-making ability,
judgment, and personality, are necessary features for the diagnosis.
Reference from
A.D.A.M.
Senile
dementia - Alzheimer's type (SDAT); SDAT
Age
and family history are risk factors for AD.
·
As
you get older, your risk of developing AD goes up. However, developing
Alzheimer's disease is not a part of normal aging.
·
Having
a close blood relative, such as a brother, sister, or parent who developed AD
increases your risk.
·
Having
certain combination of genes for proteins that appear to be abnormal in
Alzheimer's disease also increases your risk.
Other
risk factors that are not as well proven include:
·
Longstanding
high blood pressure
·
History
of head trauma
·
Female
gender
There
are two types of AD -- early onset and late onset.
·
In
early onset AD, symptoms first appear before age 60. Early onset AD is much
less common than late onset. However, it tends to progress rapidly. Early onset
disease can run in families. Several genes have been identified.
·
Late
onset AD, the most common form of the disease, develops in people age 60 and
older. Late onset AD may run in some families, but the role of genes is less
clear.
The
cause of AD is not entirely known, but is thought to include both genetic and
environmental factors. A diagnosis of AD is made when certain symptoms are
present, and by making sure other causes of dementia are not present.
The
only way to know for certain that someone has AD is to examine a sample of
their brain tissue after death. The following changes are more common in the
brain tissue of people with AD:
·
"Neurofibrillary
tangles" (twisted fragments of protein within nerve cells that clog up the
cell)
·
"Neuritic
plaques" (abnormal clusters of dead and dying nerve cells, other brain
cells, and protein)
·
"Senile
plaques" (areas where products of dying nerve cells have accumulated
around protein).
When
nerve cells (neurons) are destroyed, there is a decrease in the chemicals that
help nerve cells send messages to one another (called neurotransmitters). As a
result, areas of the brain that normally work together become disconnected.
The
buildup of aluminum, lead, mercury, and other substances in the brain is no
longer believed to be a cause of AD.
Dementia
symptoms include difficulty with many areas of mental function, including:
·
Language
·
Memory
·
Perception
·
Emotional
behavior or personality
·
Cognitive
skills (such as calculation, abstract thinking, or judgment)
Dementia
usually first appears as forgetfulness.
Mild
cognitive impairment is the stage between normal forgetfulness due to aging,
and the development of AD. People with MCI have mild problems with thinking and
memory that do not interfere with everyday activities. They are often aware of
the forgetfulness. Not everyone with MCI develops AD.
Symptoms
of MCI include:
·
Forgetting
recent events or conversations
·
Difficulty
performing more than one task at a time
·
Difficulty
solving problems
·
Taking
longer to perform more difficult activities
The
early symptoms of AD can include:
·
Language
problems, such as trouble finding the name of familiar objects
·
Misplacing
items
·
Getting
lost on familiar routes
·
Personality
changes and loss of social skills
·
Losing
interest in things previously enjoyed, flat mood
·
Difficulty
performing tasks that take some thought, but used to come easily, such as
balancing a checkbook, playing complex games (such as bridge), and learning new
information or routines
As
the AD becomes worse, symptoms are more obvious and interfere with your ability
to take care of yourself. Symptoms can include:
·
Forgetting
details about current events
·
Forgetting
events in your own life history, losing awareness of who you are
·
Change
in sleep patterns, often waking up at night
·
Difficulty
reading or writing
·
Poor
judgment and loss of ability to recognize danger
·
Using
the wrong word, mispronouncing words, speaking in confusing sentences
·
Withdrawing
from social contact
·
Having
hallucinations,
arguments, striking out, and violent behavior
·
Having
delusions, depression, agitation
·
Difficulty
doing basic tasks, such as preparing meals, choosing proper clothing, and
driving
People
with severe AD can no longer:
·
Understand
language
·
Recognize
family members
·
Perform
basic activities of daily living, such as eating, dressing, and bathing
Other
symptoms that may occur with AD:
·
Swallowing
problems
AD
can often be diagnosed through a history and physical exam by a skilled doctor
or nurse. A health care provider will take a history, do a physical exam
(including a neurological exam), and perform a mental status examination.
Tests
may be ordered to help determine whether other medical problems could be
causing dementia or making it worse. These conditions include:
·
Thyroid
disease
·
Vitamin
deficiency
·
Stroke
·
Intoxication
from medication
·
Chronic
infection
·
Anemia
·
Severe
depression
Computed
tomography (CT) or magnetic
resonance imaging (MRI) of the brain may be done to look for other
causes of dementia, such as a brain tumor or stroke.
·
In
the early stages of dementia, brain image scans may be normal. In later stages,
an MRI may show a decrease in the size of different areas of the brain.
·
While
the scans do not confirm the diagnosis of AD, they do exclude other causes of
dementia (such as stroke and tumor).
Unfortunately,
there is no cure for AD. The goals in treating AD are to:
·
Slow
the progression of the disease (although this is difficult to do)
·
Manage
behavior problems, confusion, sleep problems, and agitation
·
Modify
the home environment
·
Support
family members and other caregivers
DRUG
TREATMENT
Most
drugs used to treat Alzheimer's are aimed at slowing the rate at which symptoms
become worse. The benefit from these drugs is often small, and patients and
their families may not always notice much of a change.
Patients
and caregivers should ask their doctors the following questions about whether
and when to use these drugs:
·
What
are the potential side effects of the medicine and are they worth the risk,
given that there will likely be only a small change in behavior or function?
·
When
is the best time, if any, to use these drugs in the course of Alzheimer's
disease?
Two
types of medicine are available:
·
Donepezil
(Aricept), rivastigmine (Exelon), and galantamine (Razadyne, formerly called
Reminyl) affect the level of a chemical in the brain called acetylcholine. Side
effects include indigestion, diarrhea, loss of appetite, nausea, vomiting, muscle
cramps, and fatigue.
·
Memantine
(Namenda) is another type of drug approved for treating AD. Possible side
effects include agitation or anxiety.
Other
medicines may be needed to control aggressive, agitated, or dangerous
behaviors. These are usually given in very low doses.
It
may be necessary to stop any medications that make confusion worse. Such
medicines may include painkillers, cimetidine, central nervous system
depressants, antihistamines, sleeping pills, and others. Never change or stop
taking any medicines without first talking to your doctor.
SUPPLEMENTS
Many
people take folate (vitamin B9), vitamin B12, and vitamin E. However, there is
no strong evidence that taking these vitamins prevents AD or slows the disease
once it occurs.
Some
people believe that the herb ginkgo biloba prevents or slows the development of
dementia. However, high-quality studies have failed to show that this herb
lowers the chance of developing dementia. DO NOT use ginkgo if you take
blood-thinning medications like warfarin (Coumadin) or a class of
antidepressants called monoamine oxidase inhibitors (MAOIs).
If
you are considering any drugs or supplements, you should talk to your doctor
first. Remember that herbs and supplements available over the counter are NOT
regulated by the FDA.
For
additional information and resources for people with Alzheimer's disease and
their caregivers, see Alzheimer's disease support groups.
How
quickly AD gets worse is different for each person. If AD develops quickly, it
is more likely to worsen quickly.
Patients
with AD often die earlier than normal, although a patient may live anywhere
from 3 - 20 years after diagnosis.
The
final phase of the disease may last from a few months to several years. During
that time, the patient becomes immobile and totally disabled.
Death
usually occurs from an infection or a failure of other body systems.
·
Loss
of ability to function or care for self
·
Bedsores,
muscle contractures (loss of ability to move joints because of loss of muscle
function), infection (particularly urinary tract infections and pneumonia), and
other complications related to immobility during end stages of AD
·
Falls
and broken bones
·
Loss
of ability to interact
·
Malnutrition
and dehydration
·
Failure
of body systems
·
Harmful
or violent behavior toward self or others
·
Abuse
by an over-stressed caregiver
When to Contact a Medical Professional
Call
your health care provider if someone close to you experiences symptoms of
senile dementia/Alzheimer's type.
Call
your health care provider if a person with this disorder experiences a sudden
change in mental status. (A rapid change may indicate other illness.)
Discuss
the situation with your health care provider if you are caring for a person
with this disorder and the condition deteriorates to the point where you can no
longer care for the person in your home.
Although
there is no proven way to prevent AD, there are some practices that may be
worth incorporating into your daily routine, particularly if you have a family
history of dementia. Talk to your doctor about any of these approaches,
especially those that involve taking a medication or supplement.
·
Consume
a low-fat diet.
·
Eat
cold-water fish (like tuna, salmon, and mackerel) rich in omega-3 fatty acids,
at least 2 to 3 times per week.
·
Reduce
your intake of linoleic acid found in margarine, butter, and dairy products.
·
Increase
antioxidants like carotenoids, vitamin E, and vitamin C by eating plenty of
darkly colored fruits and vegetables.
·
Maintain
a normal blood pressure.
·
Stay
mentally and socially active throughout your life.
·
Consider
taking nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil,
Motrin), sulindac (Clinoril), or indomethacin (Indocin). Statin drugs, a class
of medications normally used for high cholesterol, may help lower your risk of
AD. Talk to your doctor about the pros and cons of using these medications for
prevention.
In
addition, early testing of a vaccine against AD is underway.
Aisen
PS, Schneider LS, Sano M, Diaz-Arrastia R, van Dyck CH, et al. High-dose B
vitamin supplementation and cognitive decline in Alzheimer's disease: a
randomized controlled trial. JAMA . 2008;300:1774-1783.
DeKosky
ST, Williamson JD, Fitzpatrick AL, Kronmal RA, Ives DG, Saxton JA, et al.
Ginkgo biloba for prevention of dementia: a randomized controlled trial. JAMA
. 2008;300:2253-2262.
Mayeux
R. Early Alzheimer’s disease. N Engl J Med . 2010 Jun
10;362(4):2194-2201.
Querfurth
HW, LaFerla FM. Alzheimer's disease. N Engl J Med . 2010 Jan
28;362(4):329-44.
沒有留言:
張貼留言