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lzheimer's
disease is a neurological disorder in which the death of brain cells causes
memory loss and cognitive decline.
It
is the most common type of dementia, accounting for 60 to 80 percent of
cases of dementia in the United States.
In 2013, 6.8 million people in
the U.S. had been diagnosed with dementia. Of these, 5 million had a diagnosis
of Alzheimer's. By 2050, the numbers are expected to double.
Alzheimer's is a neurodegenerative disease. At first, symptoms are mild,
but they become more severe over time.
Fast facts on Alzheimer's disease
·
Alzheimer's
disease is the most common type of dementia.
·
It
happens when plaques containing beta amyloid form in the brain.
·
As
symptoms worsen, it becomes harder for people to remember recent events, to
reason, and to recognize people they know.
·
Eventually,
a person with Alzheimer's is likely to need full-time assistance.
Symptoms
A person with Alzheimer's will eventually need
full-time assistance.
To receive a diagnosis of Alzheimer's, the person must have
experienced a decline in cognitive or behavioral function and
performance compared with how they were previously. This decline must interfere
with their ability to function at work or in usual activities.
The cognitive decline must be seen in at least two of the
five symptom areas listed below:
1. Reduced ability to take in and remember new information, which can
lead, for example, to:
·
repetitive
questions or conversations
·
misplacing
personal belongings
·
forgetting
events or appointments
·
getting
lost on a familiar route
2. Impairments to reasoning, complex tasking, and exercising judgment, for
example:
·
poor
understanding of safety risks
·
inability
to manage finances
·
poor
decision-making ability
·
inability
to plan complex or sequential activities
3. Impaired visuospatial abilities that are not, for example, due to eye
sight problems. These could be:
·
inability
to recognize faces or common objects or to find objects in direct view
·
inability
to use simple tools, for example, to orient clothing to the body
4. Impaired speaking, reading and writing, for example:
·
difficulty
thinking of common words while speaking, hesitations
·
speech,
spelling, and writing errors
5. Changes in personality and behavior, for example:
·
out-of-character
mood changes, including agitation, apathy, social withdrawal or a lack of
interest, motivation, or initiative
·
loss
of empathy
·
compulsive,
obsessive, or socially unacceptable behavior
If the number and severity of symptoms confirm dementia, the following
factors can then confirm Alzheimer's.
·
a
gradual onset, over months to years, rather than hours or days
·
a
marked worsening of the individual's normal level of cognition in particular
areas
If symptoms begin or worsen over the course of hours or days, you should
seek immediate medical attention, as this could indicate an acute illness.
Alzheimer's is most likely when memory loss is a prominent symptom,
especially in the area of learning and recalling new information.
Language problems can also be a key early symptom, for example, struggling
to find the right words.
If visuospatial deficits are most prominent, these would include:
·
inability
to recognize objects and faces
·
difficulty
comprehending separate parts of a scene at once
·
difficulty
with reading text, known as alexia
The most prominent deficits in executive dysfunction would be to do with
reasoning, judgment, and problem-solving.
Other early
signs
In 2016, researchers published findings suggesting that a change in sense
of humor might be an early
sign of Alzheimer's.
Recent research suggests that the features of Alzheimer's, such as brain
lesions, may already be present in midlife, even though symptoms of the disease
do not appear until years later.
Early-onset
Alzheimer's disease
Early-onset familial Alzheimer's disease can affect younger people with a
family history of the disease, typically between the ages of 30 and 60 years.
It accounts for under 5 percent of
all Alzheimer's cases.
Stages
The progression of Alzheimer's can be broken down into three main stages:
·
preclinical,
before symptoms appear
·
mild
cognitive impairment, when symptoms are mild
·
dementia
In addition, the Alzheimer's Association describes seven stages along
a continuum of cognitive decline, based on symptom severity.
The scale ranges from a state of no impairment, through mild and moderate
decline, eventually reaching "very severe decline."
A diagnosis does not usually become clear until stage four, described as
"mild or early-stage Alzheimer's."
Alzheimer's versus dementia
Dementia is an umbrella term for
a range of conditions that involve a loss of cognitive functioning.
Alzheimer's is the most common type of dementia. It involves plaques and
tangles forming in the brain. Symptoms start gradually and are most likely to
include a decline in cognitive function and language ability.
Other types of dementia include Huntington's disease, Parkinson's disease,
and Creutzfeldt-Jakob disease. People can have more
than one type of dementia.
Diagnosis
There is no single test for
Alzheimer's disease, so doctors will look at the signs and symptoms, take a
medical history, and rule out other conditions before making a diagnosis.
They may also check the person's neurological function, for example, by
testing their balance, senses, and reflexes.
Other assessments may include a blood or urine test, a CT or MRI scan of the brain, and screening for depression.
Sometimes the symptoms of dementia are related to an inherited disorder
such as Huntington's disease, so genetic testing may be done.
After ruling out other possible conditions, the doctor will carry out
cognitive and memory tests, to assess the person's ability to think and
remember.
Cognitive
assessment
To confirm a diagnosis of Alzheimer's, the following must be
present and severe enough to affect daily activities:
·
gradual
memory loss
·
progressive
cognitive impairment
Questions that may be asked to test cognitive ability include:
Alzheimer's can make it hard to remember
things.
·
What
is your age?
·
What
is the time, to the nearest hour?
·
What
is the year?
·
What
is the name of the hospital or town we are in?
·
Can
you recognize two people, for example, the doctor, nurse, or carer?
·
What
is your date of birth?
·
In
which year did (a well-known historical event) happen?
·
Name
the president.
·
Count
backward from 20 down to 1
·
Repeat
an address at the end of the test that I will give you now (for example,
"42 West Street")
A number of assessment tools are
available to assess cognitive function.
Genetic testing
In some cases, genetic testing may be appropriate.
A gene known as the APOE-e4 is associated with higher chances of people
over the age of 55 years developing Alzheimer's.
Using this test early could indicate the
likelihood of someone having or developing the disease. However, the test is
controversial, and the results are not entirely reliable.
In the future, emerging biological
tests may make it possible to assess for biomarkers in people
who may be at risk of Alzheimer's.
Treatment
There is no known cure for Alzheimer's. The death of brain cells cannot be
reversed.
However, there are therapeutic interventions that can make it easier for
people to live with the disease.
According to the Alzheimer's Association, the following are important
elements of dementia care:
·
effective
management of any conditions occurring alongside the Alzheimer's
·
activities
and day-care programs
·
involvement
of support groups and services
Drug therapy
No disease-modifying drugs are available for Alzheimer's disease, but some
options may reduce the symptoms and help improve quality of life.
Cholinesterase inhibitors that are approved for symptomatic relief in the
U.S. include:
·
Donepezil
(Aricept)
·
Rivastigmine
(Exelon)
·
Tacrine
(Cognex)
A different kind of drug, memantine (Namenda), an NMDA receptor
antagonist, may also be used,
alone or in combination with a cholinesterase inhibitor.
Other therapy
The need for quality-of-life care becomes more important as the person becomes
less able to live independently.
Results of a mouse study, published in Nature, suggested in 2016
that It may one day be possible to restore memories for people with early
Alzheimer's.
Causes and risk factors
Like all types of dementia, Alzheimer's is caused by brain cell
death. It is a neurodegenerative disease, which means there is
progressive brain cell death that happens over time.
In a person with Alzheimer's, the tissue has fewer and fewer nerve cells
and connections.
Autopsies have shown that the nerve tissue in the brain of a person with
Alzheimer's has tiny deposits, known as plaques and tangles, that build up on
the tissue.
The plaques are found between the dying brain cells, and they are made
from a protein known as beta-amyloid.
The tangles occur within the nerve cells, and they are made from another
protein, called tau.
Researchers do not fully understand why these changes occur. Several
different factors are believed to be involved.
The Alzheimer's Association has produced a journey of 16 slides that
visualizes what happens in the process of developing Alzheimer's disease. You
can access it here.
Risk factors
Unavoidable risk factors for developing the condition include:
·
aging
·
a
family history of Alzheimer's
·
carrying
certain genes
Modifiable factors that may help prevent Alzheimer's include:
·
getting
regular exercise
·
maintaining
a healthy cardiovascular system
·
managing
the risk of cardiovascular disease, diabetes, obesity,
smoking, and high blood pressure
·
following
a varied and healthful diet
·
participating
in lifelong learning and cognitive training
Some studies suggest that staying mentally and socially engaged may
possibly reduce the risk of Alzheimer's.
Factors that increase the risk include:
·
undergoing
severe or repeated traumatic brain injuries (TBI)
·
exposure
to some environmental contaminants, such as toxic metals, pesticide, and
industrial chemicals
To reduce the risk of TBI-related dementia, it is important always to wear
a safety belt when traveling by car, to take precautions when playing contact
sports, and to following health instructions and guidelines to ensure sufficient
rest and recovery if an injury does occur.
A moderate TBI appears to double the risk of
having dementia, while a severe TBI increases it 4.5 times.
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