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Alzheimer's Disease
Named after German physician Dr Alois Alzheimer, who first described
the disease in 1906, Alzheimer’s disease is a degenerative condition of
the brain, characterised by loss of memory and cognitive function.
Although there is currently no cure for Alzheimer’s disease, it can be
managed and the symptoms alleviated. A person may live from three to
twenty years with Alzheimer’s disease, with the average being seven to
ten years. Alzheimer’s is the most common form of dementia.
There are currently 500 000 Australians living with dementia. In
2004, the cost of Alzheimer’s disease alone in Australia was estimated
to be $3.6 billion. It is usually diagnosed after the age of 65. Every
five years after the age of 65, the probability of having the disease
doubles. There is also a less common form, called Familial Alzheimer’s
disease, that is directly inherited and usually affects people in their
40s or 50s.
There are currently 500 000 Australians living with dementia, Alzheimer’s being the most common form.
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Causes
Apart from Familial Alzheimer’s disease, the cause of Alzheimer’s is
not currently known. A variety of suspects, including environmental
factors, biochemical disturbances and immune processes, are being
investigated, although it is most likely to be a combination of factors
that cause the disease. It is known, however, that head injury,
particularly repeated trauma, increases the risk of developing
Alzheimer’s disease. Poor cardiovascular health and smoking have also
been linked to the disease. A genetic mutation on the ApoE gene is
implicated in Alzheimer’s and this gene, along with several other
genes, is under investigation.
The symptoms of Alzheimer’s disease are caused by the loss of nerve
cells and pathways in the areas of the brain that are vital to memory
and other mental abilities. Plaques which contain misfolded proteins
called beta amyloid form in the brain many years before the clinical
signs of Alzheimer’s are obvious. Another protein, called tau,
abnormally aggregates in the brain cells causing them to die. It is not
known if this pathology, which is used to definitively diagnose
Alzheimer’s disease after death, initiates the disease or results from
the disease.
Symptoms
Alzheimer’s disease begins slowly, with the first symptoms usually
being mild forgetfulness and visual-spatial confusion. However, as the
disease progresses, these symptoms may begin to interfere with daily
activities, such as navigating through familiar areas or recognising
people or objects.
In the middle stages of the disease, people with Alzheimer’s may
have difficulty doing basic tasks like brushing their teeth, speaking,
reading and writing. Patients may become anxious, agitated or
aggressive and will eventually need total care. In the last stages of
the disease, deterioration of musculature and mobility occurs. Patients
become bedridden and death ensues, often from pneumonia.
Currently there is no single test to identify Alzheimer’s disease. A
thorough neurological examination including testing of memory and
intellect is given along with other tests, such as blood tests, to rule
out the possibility of other diseases such as depression or nutritional
deficiencies. Once diagnosed, the symptoms of Alzheimer’s disease are
managed with a variety of treatments including drug therapy and
lifestyle modifications.
Current drugs treatments appear to provide some stabilisation in
cognitive function for some people with mild to moderate Alzheimer’s
disease, but they do not alter the progression of the disease. Drugs
may also be supplied for secondary symptoms like depression or
sleeplessness.
Together with drug therapy, cognitive and behavioural interventions
such as counselling or psychotherapy may also prove helpful throughout
the disease. Lifestyle and environmental modifications can also be very
beneficial to both the person with Alzheimer’s disease and their carer.
Activities of daily living can be aided by adhering to simplified
routines and labeling of household items to help cue the patient.
Changes in routine or environment can trigger or exacerbate agitation,
whereas adequate rest and avoidance of excess stimulation can help
prevent episodes.
Garvan is taking a range of approaches to investigate Alzheimer’s
disease. Our scientists are researching the mechanisms at the synapses
(where one neuron makes a connection with another) that are important
in memory formation and trying to understand if these mechanisms are
somehow involved in contributing to the neuron dying in Alzheimer’s
disease.
Another of our research projects involves seeing how we can harness
the brain’s own adult stem cells, which normally function to repair
injury to the brain and make new nerve cell connections, to help treat
Alzheimer’s disease as well as other neurodegenerative conditions. We
have identified a molecule that is able to stimulate neurogenesis,
which would underpin brain repair. This is important because it is
believed that brain repair could provide part of a cure for
neurodegenerative diseases. We now have an enormous amount of work to
do to understand how this molecule acts to bring about this
regeneration, determine if the molecule has any therapeutic potential,
and identify other molecules that may be important for stimulating
regeneration and stem cell therapies.
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