- [Voiceover] Let's say you're
going to the grocery store, but you realize you left
your keys in your room. You go up to get them and
then walk into the room and look around for a second,
and realize you completely forgot why you even came
here in the first place. We all know how frustrating
this can be, right? But this scenario is totally
normal and is something everybody experiences from time to time. And besides causing you
to take one more trip up the stairs to your room
after you remember again, it doesn't throw off your day too much. When problems remembering or problems with your thinking skills
in general become so severe and so common that they actually interfere with your daily life, it might
be diagnosed as dementia. Dementia, though, is
not a specific disease. What do I mean by that? Well, it's more of a
general term that describes a range of potential
difficulties with reasoning, judgement, and memory. For example somebody with
dementia might have troubles with speaking or writing
coherently, or understanding what was spoken or written. They also might have trouble
recognizing their surroundings, especially when those
surroundings should normally be very familiar to them. Planning and performing tasks
that require multiple steps can also be difficult for
patients with dementia. Even tasks that you might
think are really simple, like getting dressed and
eating, these can become a serious challenge for patients
with later-stage dementia. And to make matters worse,
many times, patients aren't even aware that they're
experiencing any troubles or any sort of cognitive
deficiencies at all. Now, dementia is most
common in the elderly, especially after age 65. But it is certainly not
a normal part of aging. So, dementia, in very general
terms, is something we use to describe when someone
has troubles learning, remembering, and communicating. But where does Alzheimer's
Disease fit into this? Well, Alzheimer's Disease
is a type of dementia. Specifically, it's what's known as a neuro degenerative
disease, and it counts for about 60 to 80% of all cases of
dementia, affecting about five million people. So, if we look at "neuro,"
we know that this refers to the nerves of the nervous system, or basically your brain,
and then, "degenerative" or "degeneration" means to
decline or to deteriorate. So, with Alzheimer's Disease,
there's this deterioration of your nerve cells in your brain. And this brain of yours
houses about a hundred billion nerve cells, which are
also called neurons. And these guys communicate using a hundred trillion connections. That's a lot. Now, this communication
and those connections are what control essentially
every other organ and every other function in your body, not to mention your thinking abilities. Unfortunately, though,
the main type of cells that Alzheimer's Disease
targets and affects are these precious neurons. And depending on where
the affected neurons live in your brain, different
functions of your brain can be affected. For example, if nerve cells
in this area of your cerebrum are affected, you might have
trouble solving problems or making plans, because
these cells help you do those things. Or, if the neurons in
this area are affected, you might have problems
remembering something or storing new memories. And as Alzheimer's Disease progresses, more and more of these
neurons die, and your brain tissue actually begins to
shrink due to this loss of nerve cells. All right. So, nerve cells in your
brain are destroyed in Alzheimer's Disease,
but how are they destroyed? Well, unfortunately, answers
to seemingly fundamental questions like these aren't
really fully understood yet. But scientists have pinpointed
a couple of possible culprits that usually seem to be involved, and these are called plaques and tangles. Plaques are like these
weird, abnormal clusters of protein fragments that build up between neighboring neurons. So, this is a normal group
of nerve cells going about their business, you know,
communicating and what-not. With Alzheimer's Disease,
these plaques start to form in between these neurons,
which is thought to make it a lot harder for them to communicate. Now, besides plaques, the other hallmark of Alzheimer's Disease are called tangles. Unlike plaques, though,
these guys are found inside the neurons, and most of
these are made up of a protein called tau. And tau proteins are helpful usually, but in Alzheimer's Disease,
they're all twisted and abnormal, which ultimately
ends up hurting the cells. Okay. But we still haven't
said why these plaques and tangles form. Well, again, that question
is still a huge, huge area of research, and is something
scientists continue to gain insight on but have yet
to completely understand.