Alzheimer's disease is the most common cause of dementia,
which is the loss of intellectual and social abilities
severe enough to interfere with daily functioning. Dementia
occurs in people with Alzheimer's disease because healthy
brain tissue degenerates, causing a steady decline in
memory and mental abilities.
More than 4 million older Americans have Alzheimer's,
a disease that usually develops in those age 65 or older.
This number is expected to quadruple by the year 2050
as more people live into their 80s and 90s.
Although there's no cure for Alzheimer's disease, researchers
have made progress. Treatments are available that help
improve the quality of life for people with Alzheimer's.
Also, more drugs are being studied, and scientists have
discovered several genes associated with Alzheimer's,
which may lead to new treatments to block progression
of this complex disease.
In the meantime, caring for someone with Alzheimer's
takes patience and a focus on the things a person can
still do and enjoy. Those with Alzheimer's — as
well as those who care for them — need support
and affection from friends and family to cope.
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Everyone has occasional lapses in memory. It's often
quite normal to forget the names of people whom you
rarely see. But it's not a normal part of aging to forget
the names of familiar people and objects.
Alzheimer's disease — which is a progressive
(degenerative) brain disease — goes beyond simple
forgetfulness. It may start with slight memory loss
and confusion, but it eventually leads to irreversible
mental impairment that destroys a person's ability to
remember, reason, learn and imagine.
Most people with Alzheimer's share certain signs and
symptoms of the disease. These may include:
• Increasing and persistent forgetfulness.
At its onset, Alzheimer's disease is marked by periods
of forgetfulness, especially of recent events or simple
directions. But what begins as mild forgetfulness persists
and worsens. People with Alzheimer's may repeat things
and forget conversations or appointments. They routinely
misplace things, often putting them in illogical locations.
They frequently forget names, and eventually, they may
forget the names of family members and everyday objects.
• Difficulties with abstract thinking.
People with Alzheimer's may initially have trouble balancing
their checkbook, a problem that progresses to trouble
recognizing and understanding numbers.
• Difficulty finding the right word.
It may be a challenge for those with Alzheimer's to
find the right words to express thoughts or even follow
conversations. Eventually, reading and writing also
are affected.
• Disorientation. People with
Alzheimer's may lose a sense of time and dates. They
may find themselves lost in familiar surroundings. Eventually,
they may even wander from home.
• Loss of judgment. Solving
everyday problems, such as knowing what to do if food
on the stove is burning, becomes increasingly difficult,
eventually impossible. Alzheimer's is characterized
by greater difficulty in doing things that require planning,
decision making and judgment.
• Difficulty performing familiar tasks.
Once-routine tasks that require sequential steps, such
as cooking, become a struggle as the disease progresses.
Eventually, people with advanced Alzheimer's may forget
how to do the most basic things.
• Personality changes. People
with Alzheimer's may exhibit mood swings. They may express
distrust in others, show increased stubbornness and
withdraw socially. Early on, this may be a response
to the frustration they feel as they notice uncontrollable
changes in their memory. Depression often coexists with
Alzheimer's disease. Restlessness also is a common sign.
As the disease progresses, people with Alzheimer's may
become anxious or aggressive and behave inappropriately.
Typically, loved ones notice very gradual — not
sudden — changes in a person with Alzheimer's.
As the disease progresses, symptoms become serious and
noticeable enough to cause people with Alzheimer's or
their family members to seek medical help. Many people
with Alzheimer's disease realize that something is happening
to their memory, which can be frightening.
The course the disease takes and how rapidly changes
occur vary from person to person. For some, the progression
from simple forgetfulness to severe dementia takes five
years. For others, it can take a decade or longer.
Alzheimer's generally progresses from mild to moderate
to severe to, finally, profound impairment. People with
mild Alzheimer's can usually live alone and function
fairly well. Those with moderate Alzheimer's may have
greater difficulty coping without supervision. People
with advanced Alzheimer's generally can no longer care
for themselves.
Researchers have identified a state of memory loss
called mild cognitive impairment that could potentially
be known as a pre-Alzheimer's period. This memory loss
falls somewhere between what's associated with normal
aging and what's common in Alzheimer's disease. People
with mild cognitive impairment may experience forgetfulness
beyond what's typical for their age, yet they don't
have the dementia of Alzheimer's. Identification of
this category of memory loss could help doctors more
accurately diagnose, advise and treat these people.
It could also alert these people to a greater risk of
developing Alzheimer's disease.
In the past, people called dementia senility and considered
it an inevitable part of aging. Doctors now know that
dementia isn't a normal part of aging and that it's
caused by some underlying condition affecting the brain.
Many different conditions can cause dementia. Alzheimer's
disease accounts for more than half of all dementia
cases. However, as many as 50 other conditions may cause
dementia. Some are treatable, such as depression. That
makes it important to diagnose the particular signs
and symptoms of a dementia and attempt to identify its
underlying cause.
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The causes of Alzheimer's aren't well understood. But
researchers have found that people with Alzheimer's
have brain cells that become damaged and die for unknown
reasons.
A healthy brain has about 100 billion nerve cells called
neurons. Neurons generate electrical and chemical signals
that are relayed from neuron to neuron to help you think,
remember and feel. Chemicals called neurotransmitters
help these signals flow seamlessly between neurons.
Initially in people with Alzheimer's, neurons in certain
locations of the brain begin to die. As they die, lower
levels of neurotransmitters are produced, creating signaling
problems in the brain.
Alzheimer's disease is named after German neurologist
Alois Alzheimer, M.D. In 1906, he examined the brain
of a woman who had died after years of progressive dementia.
Her brain tissue showed abnormal clumps and irregular
knots of brain cells. Today, these clumps (now called
plaques) and knots (now called tangles) are considered
hallmarks of Alzheimer's disease.
Researchers continue to study these abnormal structures
— plaques and tangles — to better understand
why brain cells slowly die in people with Alzheimer's.
In the meantime, scientists have theories that may explain
how these structures are involved in Alzheimer's disease:
• Plaques. Plaques are made
up of a normally harmless protein called amyloid-beta.
It's believed deposits of plaque form between neurons
early on in the disease process, before neurons begin
to die and symptoms develop. Although the ultimate cause
of neuron death in Alzheimer's isn't known, mounting
evidence suggests that a form of amyloid-beta protein
may be the culprit. Three genetic mutations —
in amyloid precursor protein (APP) and presenilin 1
(PS1) and presenilin 2 (PS2) proteins — are known
to cause a small number of early-onset forms of Alzheimer's
disease. These mutations result in the production of
amyloid plaques. Together, these three genetic mutations
account for less than 10 percent of all Alzheimer's
cases.
• Tangles. The internal support
structure for brain neurons depends on the normal functioning
of a protein called tau. In people with Alzheimer's,
threads of tau protein undergo alterations that cause
them to become twisted. Many researchers believe this
may seriously damage neurons, causing them to die.
Inflammatory responses
Researchers have observed profound inflammation in
the brains of some people with Alzheimer's disease.
Inflammation is your body's response to injury or infection
and a natural part of the healing process.
Even as beta-amyloid plaques develop in the spaces
between neurons, immune cells (microglia) are at work
getting rid of dead cells and other waste products in
the brain. Scientists speculate that the microglia may
view plaques as foreign substances in the body and try
to destroy them, triggering the inflammatory response.
Or the microglia may be trying to remove damaged neurons.
The microglia may also activate other compounds that
cause inflammation. These include the protein interleukin-1,
the enzyme COX-2 and a group of proteins, known as complement,
which take action against cells marked by microglia
for attack. Although researchers believe the inflammation
occurs before plaques have fully formed, they aren't
sure how this development relates to the disease process.
There's also debate about whether inflammation has a
damaging effect on neurons or whether it is beneficial
in clearing away plaques.
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Alzheimer's is a complex disease that's likely caused
by a variety of influences. Although all of these influences
may never be known, scientists have identified several
risk factors that may increase the likelihood of developing
Alzheimer's disease. They include:
• Age. Alzheimer's usually
affects people older than 65, but can, rarely, affect
those younger than 40. The average age at diagnosis
is about 80. Only one to two people in 100 have Alzheimer's
at 65, but that risk increases to about one in five
by 80. By age 90, half of all people have some symptoms.
Women are more likely than men to develop the disease,
in part because they live longer.
• Heredity. Your risk of developing
Alzheimer's appears to be slightly higher if a first-degree
relative — parent, sister or brother —
has the disease. Although the genetic mechanisms of
Alzheimer's among families remain largely unexplained,
researchers have identified a few genetic mutations
that greatly increase risk in some families. Three
genetic mutations are known to cause early-onset Alzheimer's.
In addition, one form of the apolipoprotein E (APOE)
gene increases your chance of developing the late-onset
Alzheimer's.
• Environment. Researchers
are studying environmental factors to discover both
the possible causes and the prevention of Alzheimer's.
For example, some people with Alzheimer's have deposits
of aluminum in their brain. But scientists who've
studied environmental sources of aluminum —
everything from antiperspirants to drinking water
— haven't found a link between aluminum exposure
and Alzheimer's. Investigators have also looked at
smoking and exposure to occupational hazards such
as glues, pesticides, fertilizers or even electromagnetic
fields as potential contributors to Alzheimer's. Results
from all of these investigations, however, have been
inconsistent, and at this point, there's still no
irrefutable evidence regarding any environmental or
lifestyle factor increasing a person's risk of Alzheimer's.
• Degree of mental activity.
Some studies have suggested that low education may
increase your risk of Alzheimer's disease. Other studies
have shown that remaining mentally active throughout
your life, especially in your later years, reduces
the risk. These studies have supported the notion
that people might be able to impact their risk of
Alzheimer's based on their mental activity. However,
changes related to Alzheimer's occur in the brain
decades before the disease becomes evident through
changed behavior. Thus, it remains unclear whether
lower education creates a risk of Alzheimer's or if
it's simply easier to detect Alzheimer's in people
with lower education.
• Head injury. The observation
that some ex-boxers eventually develop dementia leads
to the question of whether serious traumatic injury
to the head (for example, with a prolonged loss of
consciousness) may be a risk factor for Alzheimer's.
Several studies indicate a definite link between the
two, especially for men. Other studies find only a
slight, nonsignificant correlation between head trauma
and Alzheimer's.
• Hormone replacement therapy.
Findings published in the May 28, 2003, Journal of
the American Medical Association indicate that women
using combination hormone therapy — estrogen
plus progesterone — double their risk of dementia,
including Alzheimer's disease.
• Others. A number of studies
suggest a positive correlation between Alzheimer's,
high blood pressure and high cholesterol. Depression
also has been identified as a possible risk factor
for Alzheimer's disease.
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There's no one test to diagnose Alzheimer's disease.
Instead, doctors diagnose Alzheimer's disease through
a process of elimination — ruling out other diseases
and conditions that also can cause memory loss.
Small, undetected strokes, for example, can cause
dementia by temporarily interrupting blood flow to the
brain. People with Parkinson's disease, a degenerative
nerve disease, also can develop dementia. Depression
can cause lapses in memory. In addition, many older
adults are on multiple medications that may impair their
ability to think clearly.
To help diagnose Alzheimer's disease from other causes
of memory loss — which are often treatable —
doctors typically rely on the following:
• Medical history. Doctors may
ask about a person's general health and past medical
problems. They'll want to know about any problems a
person may have in carrying out daily activities. If
possible, doctors will also want to speak with a person's
family or friends to get more information.
• Basic medical tests. Blood
and urine tests may be done to help doctors rule out
other potential causes of the dementia. In some cases
testing a small amount of spinal fluid also may help.
• Mental status evaluation.
These tests screen memory, problem-solving abilities,
attention spans, counting skills and language. They
help doctors pinpoint specific problems a person may
have with cognition. For instance, doctors might test
recent and long-term memory by asking: What day is it
today? Or, when was World War II? Recall tests are another
example. Doctors may list familiar objects, and then
ask a person to repeat them immediately, and again five
minutes later.
• Neuropsychologic testing.
Sometimes doctors undertake a more extensive assessment
of memory, problem-solving abilities, attention spans,
counting skills and language. This is especially helpful
in trying to detect Alzheimer's and other dementias
at an early stage. Doctors use formal psychological
tests to determine if a person's mental abilities are
as expected for their age and education. The patterns
of any mental deficits observed during neuropsychologic
testing can help doctors sort out possible causes of
dementia.
• Brain scans. Doctors may want
to take a picture of the brain using a brain scan. Several
types of brain scans are available — including
a computerized tomography (CT) scan, a magnetic resonance
imaging (MRI) scan and a positron emission tomography
(PET) scan. By looking at a picture of the brain, doctors
may be able to pinpoint any visible abnormalities
Using the methods above, doctors can accurately diagnose
90 percent of Alzheimer's cases. Alzheimer's can be
diagnosed with 100-percent accuracy only after a microscopic
examination of brain tissue, which checks for plaques
and tangles.
Genetic testing for Alzheimer's is in its infancy stages.
Blood tests are available that can tell whether a person
carries genetic mutations believed associated with Alzheimer's,
but the tests can't tell who will or will not get the
disease.
If you or someone you know has been diagnosed
with Alzheimer's or Parkinson's, please read the online
article from CBS's 60 Minutes - Saved
From Senility. A small number of Alzheimer's and
Parkinson's cases may actually be NPH - Normal Pressure
Hydrocephalus, which is treatable.
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Currently, there's no cure for Alzheimer's disease.
Medications and caregiving are the primary treatments.
Medications
Current medications for Alzheimer's can't stop or
reverse the underlying disease process. But they may
slow it down, lessening signs and symptoms. Medications
commonly recommended for people with mild to moderate
Alzheimer's include:
• Donepezil (Aricept). This medication decreases
mild to moderate symptoms of Alzheimer's by improving
levels of neurotransmitters in the brain.
• Rivastigamine (Exelon). Like donepezil, rivastigamine
blocks the breakdown of neurotransmitters in the brain,
lessening symptoms.
• Galantamine (Reminyl). Galantamine is a newer
medication to treat Alzheimer's. It improves both cognition
and behavior.
Tacrine (Cognex) is another drug that's available for
mild to moderate Alzheimer's. Tacrine has been on the
market since 1993. However, doctors rarely prescribe
this drug because of serious side effects, including
possible liver damage.
In October 2003, the Food and Drug Administration approved
the drug memantine (Namenda), the only medication specifically
indicated for treatment of moderate to severe stages
of Alzheimer's. Memantime seems to slow the loss of
daily living skills, such as dressing and going to the
bathroom. The drug works by protecting brain cells from
damage caused by the chemical messenger glutamate.
Doctors also sometimes prescribe drugs to improve behavioral
symptoms that often accompany Alzheimer's, including
sleeplessness, wandering, anxiety, agitation and depression.
Today, treatment of Alzheimer's disease is still in
its infancy. But researchers are confident that in the
not-too-distant future, new medications should be available
that do more than treat the symptoms of Alzheimer's.
Caregiving
Until there's a cure for Alzheimer's, people with
the disease will need caregiving. According to the Alzheimer's
Association, approximately one in 10 families have a
relative with Alzheimer's disease. Of the 4 million
people with Alzheimer's disease in the United States,
the majority live at home — often receiving part-
or full-time care from family members.
Caregiving can be a challenge. The slow and unpredictable
decline that may last more than a decade requires caregivers
to exercise patience, understanding, compassion, and
often, creativity.
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Right now, there's no way to prevent the onset of Alzheimer's
disease. But researchers continue to look for ways to
reduce risk of the disease. Several leads are hopeful,
but preliminary. They include:
• Nonsteroidal anti-inflammatory drugs
(NSAIDs). A study released in 1996 showed that
the NSAIDs ibuprofen (Advil, Motrin, others), naproxen
sodium (Aleve) and indomethacin (Indocin) reduced the
risk of developing Alzheimer's. Doctors believe brain
inflammation occurs as one part in the development of
Alzheimer's. Investigators were uncertain why aspirin,
which also is an anti-inflammatory drug, and acetaminophen
(Tylenol, others), which is not, had no effect. NSAIDs
can cause gastrointestinal bleeding. For this reason,
clinical trials need to be completed before it's clear
whether doctors should recommend that people take NSAIDs
solely to prevent Alzheimer's.
• Vitamin E and selegiline.
Researchers are studying whether vitamin E and selegiline
(Eldepryl), a drug used to treat Parkinson's disease,
may hold a possible protective effect against the progression
of Alzheimer's. These substances may slow the rate of
decline in people with moderately severe Alzheimer's.
Vitamin E and selegiline are antioxidants and may help
prevent brain cell damage by destroying toxic free radicals.
Free radicals are byproducts of normal cell function.
Some scientists believe free radicals are discharged
by immune cells that are in the brain responding to
chronic brain inflammation from Alzheimer's. The free
radicals may attach to molecules in brain cells and
disrupt brain cell function. Findings of the only large
clinical trial to date, with regard to these antioxidants,
were published in the April 24, 1997, issue of the New
England Journal of Medicine. In the trial, people with
moderate Alzheimer's who were given selegiline or high
doses of vitamin E, or a combination of both, experienced
a seven-month delay in the progression of the disease.
• Estrogen. Alzheimer's disease
in older women may be related to estrogen deficiency.
Estrogen helps keep the brain healthy by boosting production
of a key neurotransmitter, helping prevent deposits
of plaque and improving blood flow to the brain. Studies
show that hormone replacement therapy after menopause
can reduce a woman's risk of developing Alzheimer's
by 40 percent to 50 percent. However, the results of
the largest and longest trial to date involving estrogen
and women with Alzheimer's, published in 2000, showed
no differences between the women who received estrogen
replacement therapy and those who didn't after one year.
A smaller trial also showed no benefit in administering
estrogen for preventing Alzheimer's. Because the impact
of estrogen still isn't proved, women shouldn't begin
hormone replacement therapy solely to prevent Alzheimer's
without the approval of their doctor.
• Mental fitness. Maintaining
mental fitness may delay onset of dementia. Some researchers
believe that lifelong mental exercise and learning may
promote the growth of additional synapses, the connections
between neurons, and delay the onset of dementia. Other
researchers argue that advanced education gives a person
more experience with the types of memory and thinking
tests used to measure dementia. This advanced level
of education simply may help some people "cover
up" their condition until later.
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* Text Resources: The Mayo Clinic Staff
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