Alzheimer’s disease, a common form of dementia, is a
progressive brain disease that eventually leads to death.
Firstly it had been described by a German Psychiatrist named
Alois Alzheimer. The most common incidence of this disease is
in people who are above the age of 65. Although the disease
tends to develop and progress differently in different people,
but still there are some common symptoms which can be observed
in all of them. As of the year 2006, there were about 27
million suffering from this disease all over the world.
The early effectuations and symptoms of this disease are
mistaken to the influences of age and stress related issues.
The diagnosis of this disease is confirmed by making use of
several psychological and medical tests including the FMRI
scan which gives a clear image of the influenced areas. In
terms of the etiology of the disease, nothing can be said for
sure. Most of the research which has been carried out in this
regard has shown that the disease occurs due to the formation
of plaques and tangles in various brain regions.
The disease has been classified into four different categories
and stages. All these stages are marked for their progressive
patterns of cognitive as well as functional impairments.
One of the first symptoms of this disease are often confused
or mistakenly taken to be the age related symptoms, but
through the conduction of some detailed neuropsychological
testing, the presence of this disease can be confirmed. There
is a specific diagnostic criteria which should be followed for
the confirmation of the disease and its specific stage. The
early symptoms include minor levels of losses in short term
memory, confusing things, minor levels of speech impairment
and some others.
In the patients suffering from AD, a significant impairment in
the learning as well as memory helps in making a definitive
diagnosis about this disease. In some small portions of them,
deficiencies and difficulties in executive functions, motor
control-apraxia, perception-agnosia and speech impairment are
more prominent that all others. The older memories including
the episodic and semantic memory are effectuated to lower
level or degree.
The problems which the person experiences in terms of the
language are marked by a shrinking vocabulary, word fluency
and written language. In terms of this stage, the people with
AD are able to communicate while using basic forms of
language. In other words, they are still able to communicate
their basic ideas. As the disease tends to worsen, people with
AD would be able to perform all of their tasks independently,
but will still need some form of assistance in one form or the
other.
The progressive levels of deterioration tend to influence all
independent functions due to which the subjects are less able
to carry out their daily activities.
With the passage of time, the speech difficulties get more
and more visible, thus leading to a frequent paraphasias-also
referred to as incorrect word substitutions. Moreover, the
motor sequences also become less coordinated as the person
progresses into the disease. During this specific phase, the
memory problems grow more worse due to which the person might
fail in the recognition of the familiar people. That’s not
all, as the long term memory, which was previously seen to be
intact, also gets impaired.
As this stage is the final and the most severe one, all the
symptoms are the worst ever in this stage.
This is the reason for which the patient is completely
dependent upon the caregivers. Despite of a severe loss in
motor, language and cognitive abilities, the person might
still be able to convey some distinct emotional reactions. Due
to the loss of the muscle mass, most of them lose their
ability to feed themselves. As AD is known to be a terminal
disease, the death of the patient most of the times occurs due
to an external factor including the infections, pressure
ulcers, pneumonia.
The exact causes of the disease are still unknown, but there
are some hypothesis which are able to provide an explanation
in this regard. This hypothesis states that AD occurs due to
the deficiency in the neurotransmitter acetylcholine. It has
not managed to gain a wide support, as the medications that
improve the acetylcholine synthesis and production have failed
to cause an improvement.
This hypothesis had been proposed in the year 1991. It states
that the prime cause of AD is a beta-amyloid. The support for
this hypothesis comes from the presence of the amyloid protein
precursor on the chromosome 21 in addition to the fact that
people suffering from the Down syndrome also exhibit AD as the
reach the age of 40. In the year 2009, some modification were
made in this theory stating that a close relative of the
specific protein under discussion might also be the cause of
this disease.
In lines to this hypothesis, the varying abnormalities due to
the tau protein might be the initiating factor behind the
disease cascade. Eventually, they lead to the formation of the
neurofibrillary tangles. Research has suggested that among the
vast majority of the causal factors, no formal evidence has
been found in terms of the role of genes, but there are some
gene factors that might be classified as the risk factors.
Among the cases, around 0.1 % of them happen to be familial
forms and types of autosomal dominant, which cannot be termed
as a sex linked inheritance.
Most of the cases of AD seen till now are sporadic which
means that the disease has not been inherited genetically.
Nevertheless, the varying number of genetic differences might
come to act as the risk factors. Around 40 to 80 % of the
people with AD have a presence of APOEε4 allele in their
different brain regions. The geneticists are of the view here
that there are also a number of other genes which might be
termed as being the risk factors.
It can be said here that the researches that will be made
in the future will lead to some more definitive results.
Evidence suggests that the same allele does acts as a factor
behind the onset of the disease.
AD is most of the times diagnoses using the clinical history
of the patient, through clinical observations,
neuropsychological testing and by performing a collateral
history analysis of the family members.
Advanced forms of medical imaging including computed
tomography, functional magnetic resonance imaging, positron
emission tomography and other state of the art procedures have
advanced the detection methods of AD. Moreover, these devices
and procedures also reveal information about the specific
stage of the disease.
In addition, the assessment procedures used to access
the intellectual functioning of the patients also help in a
further characterization of the specific stage of the disease.
Medical organizations and authorities have also set a
diagnostic criteria in order to ease and standardize the
diagnosis of this disease.
The presence of this disease can also be confirmed through
the performance of a post-mortem analysis.
Another latest procedure in terms of the diagnosis involves
the analysis of the cerebrospinal fluid (CSF). The fluid is
analyzed for the presence of the beta amyloid together with
the tau proteins both of which are functional in the onset of
the disease.
These proteins are traced using a procedure called a spinal
tap which has the potential to detect the onset of AD with a
sensitivity level close to 94 to 100 %. The tests for the
spinal fluid analysis are now commercially available, but the
same is not true for the neuroimaging devices. AD was also
detected in those people who showed no symptoms which means
that the progress of the disease occurs well before the
symptoms start to appear.
