What is Alzheimer’s?
Alzheimer’s is a
type of dementia that is characterised by problems with memory and behaviour. Dementia
is a general term for memory loss or cognitive issues such as language,
learning, comprehension and social functioning. Alzheimer’s is the most common
type of dementia and accounts for 60-80% of cases. Symptoms usually begin to
slowly develop and over time, can become severe enough where those affected may
not be able to live on their own. Symptoms start with things such as
forgetfulness and difficulty concentrating, which may be hard to notice at
first. As time progresses, symptoms usually worsen to more severe memory loss
and can even lead to changes in personality or mood. People living with Alzheimer’s
have, on average, 8 more years to live, after their diagnosis.
The risk of
developing Alzheimer’s increases with age. The average age of people with Alzheimer’s
is 65 and older. Although a majority of cases are of elderly people, there can
also be early onset Alzheimer’s which accounts for around 5% of cases. In
addition to the risk increasing with age, Alzheimer’s also worsens over time.
What Causes Alzheimer’s?
Scientists don’t know the exact reasons for what causes Alzheimer’s,
but they do know that patients develop two major features in their brains. One
of these is plaques which are deposits mostly made up of a protein called
amyloid beta. The other feature is tangles of a protein called tau which are
formed inside of neurons. Normal people still develop some of these plaques and
tangles as they age but patients with Alzheimer’s have much more of them. These
plaques and tangles in patients are also ale to spread through to unaffected
areas of the brain as their illness worsens.
The best idea that scientists have been able to come up
with is called the amyloid hypothesis. The amyloid hypothesis suggests that a build-up
of the protein amyloid beta is the main cause for Alzheimer’s. Scientists
believe that the plaques cause a disruption in the communication between brain
cells. In addition to forming bundles of plaque, amyloid beta can also form
bundles that dissolve into the fluid in the brain. This can cause harmful
inflammation when the immune system tries to clear these out.
This hypothesis still doesn’t take into account how the
tau proteins affect the brain. Scientists have found that these tangles of tau appear
to form after the amyloid beta plaques and lead to even more brain damage. Tau
is normally used to stabilise microtubules which are tiny structures neurons use
to transport nutrients and neurotransmitters around the cell. When tau doesn’t
function as normal and forms the tangles, it disrupts the signalling and
transport within the cell. As the amyloid beta plaques, inflammation, and
tangles of tau build-up and progress, they begin to disrupt the systems and
functions of the brain.
There is currently no know way of reversing the forming
of these plaques and tangles. Scientists are also not sure what causes these
plaques and tangles to start developing in the first place. Many scientists
believe the reason for Alzheimer’s includes several factors such as genetics,
the environment, and overall health.
One known definite
cause of Alzheimer’s which accounts for approximately 1% of cases is caused by
a genetic mutation in the amyloid-related genes PSEN1 or PSEN2 or in a protein
that gets processed into amyloid beta (APP). You only need to inherit one copy
of the mutated gene to develop familial Alzheimer’s. Unlike normal onset of
dementia which usually starts showing symptoms around 65 or older, these cases
show up earlier; around 40 to 50.
Is It Possible to Cure Alzheimer’s?
Even though we still
don’t understand everything on how Alzheimer’s and other forms of dementia affect
our brains, there is no reason why they should be impossible to prevent or
cure. Scientists have been continuing to research how dementia affects the
brain and possible ways to prevent or even cure Alzheimer’s.
There are currently
no available cures for Alzheimer’s but there are many treatment options to help
and slow the progression of the disease. The two main types of drugs used for
treating Alzheimer’s are acetylcholinesterase inhibitors and NMDA antagonist.
The acetylcholinesterase inhibitors increase levels of the neurotransmitter
acetylcholine in the brain by blocking the enzyme that normally breaks it down.
This can help to ease the cognitive symptoms of Alzheimer’s.