- You may have heard of Parkinson's disease before.
Maybe when you heard of someone raising money
for the Michael J. Fox Foundation,
or maybe you've listened to Muhammad Ali
speaking about the disease.
Both of these guys actually have Parkinson's disease,
and they've done a really good job
at raising money for, and awareness of, the disease.
But what exactly is Parkinson's disease?
Parkinson's disease is a progressive
neurodegenerative disease.
We call it a progressive disease
because it progresses.
It worsens over time.
We say that it's a neurodegenerative disease
because during the disease
there's actually a loss, a degeneration,
of neurons in the brain.
In Parkinson's disease, we actually see
a loss of a particular kind of neuron,
and these neurons are called dopamine neurons.
Dopamine neurons make a little signalling chemical
called dopamine, which is really important
for allowing us to make normal movements.
A lot of these dopamine neurons
live in an area of the brain called the substantia nigra.
The substantia nigra we can see here.
It sits here in the brain, above the spinal cord,
in the part of the brain called the midbrain.
When these neurons are lost, there's a reduction
in the amount of dopamine in the brain.
Again, that's because these neurons,
they're used to make a lot of our dopamine
and now they're not here anymore.
And this is the really important part,
because when there's this reduction in dopamine
that's when we start to see
the main movement signs of Parkinson's disease.
Let's talk about these signs.
One of these signs is shakiness,
which can often be in the form of a tremor,
maybe in the hand or the finger.
A second sign is stiffness.
That stiffness is felt when the person
bends part of their body.
Maybe the arm or the leg or the wrist.
When they're bending that body part,
let's say it's the arm,
the movement just isn't very smooth.
It doesn't feel very fluid anymore.
Instead it actually feels really rigid.
A third sign is slowed-down movements.
This happens because it actually takes the person
longer to complete a movement.
A good way to think about this
is to imagine the last time you were in water.
Maybe you went to the pool,
or you went to the beach to go swim in the ocean.
You can probably remember trying to do
a somersault underwater,
or maybe running away from your friends.
If you think back, you can remember
that it actually took you a lot longer
to do these things in water
than it would have if you were on land.
That's kind of what it's like
for someone with these slowed-down movements.
They can do them.
It just takes a lot longer for them to do them.
The fourth main sign is problems with balance.
Feeling really unsteady, or really unstable
when standing or walking around.
Now, not all patients with Parkinson's disease
will have all of these problems,
but most will have them at some point
during the course of the disease.
Now, this last one that we talked about,
the problems with balance,
that usually crops up later on,
once the person has had the disease
for quite a few years.
It's actually these first three that are normally used
to decide whether or not someone has Parkinson's disease.
All these main movement signs together
actually form a symptom complex
called Parkinsonism,
or Parkinsonian syndrome.
That means that Parkinson's is actually a disease
that causes Parkinsonism.
There are a few other neurodegenerative diseases
that can cause Parkinsonism,
this symptom complex that we're talking about.
But Parkinson's disease is the most common,
so because of this, we often call Parkinsonism
caused by Parkinson's disease Primary Parkinsonism,
and then we often called Parkinsonism
caused by other neurodegenerative diseases
Secondary Parkinsonism.
Now, Parkinson's disease doesn't just cause Parkinsonism.
Remember that this is a disease of the brain,
and when things break down in our brain,
our master control center, there's often
more than one kind of symptom.
People with Parkinson's disease can also experience
psychiatric problems such as depression,
cognitive problems such as memory loss
and trouble with concentration,
and lots of other non-movement symptoms.
This can include problems with their sense of smell
and problems with their sleeping patterns.
The causes of Parkinson's disease
are actually largely not known.
For the majority of cases,
we actually don't know what triggered the disease,
so we call these cases ideopathic.
"Ideopathic" meaning that the cause is unknown.
While in the vast majority of cases
there is no family history of the disease,
about 15% of people actually do have a family history
and for these people their Parkinson's
appears to be caused by a mutation
in one of a few different genes.
Depending on which gene is the culprit,
a mutation can either cause Parkinson's disease
or it can increase a person's chance
of getting Parkinson's disease.
If someone has a problem with one of the genes
that can actually cause the disease
they'll definitely develop it, but if they have a problem
with one of the genes that can increase
the chance of getting Parkinson's disease,
they may or may not develop the disease,
but they are more likely to
than someone who doesn't have the mutated gene.
Genetics are the culprit once in a while,
but again, most of the time,
we don't know what caused Parkinson's disease.
Despite this, there are some risk factors
associated with developing the disease.
A risk factor is something that increases
your chances of developing a disease.
You could say that having a certain gene mutation
is a major risk factor for Parkinson's,
but there are some other non-genetic risk factors as well.
For example, exposure to certain pesticides
and some cleaning chemicals.
Older age, so once you get to about 60 years old
your risk of developing Parkinson's disease increases
and it continues to go up with each passing year.
So as well we have a history of concussions
as a risk factor of Parkinson's disease,
and gender.
For some reason, we're not entirely sure yet,
men are a bit more likely than women
to develop the disease.
Another risk factor is regularly breathing in
heavy metal particles like copper
or manganese or lead.
Maybe if you've lived in an industrial area
where those might be found in the air.
Again, these are risk factors for Parkinson's disease,
which means that they're associated with
a higher chance of developing the disease.
The treatment of Parkinson's disease
will normally involve medication
to help deal with the movement symptoms,
and to do that, the way that many of these medications work
is by replacing or increasing dopamine levels in the brain
because remember, our dopamine-producing neurons
have degenerated during the disease,
and for some patients, the medication works great.
It may be all that they need to minimize the symptoms.
But for most patients, after they've had the disease
for several years, their medication
just doesn't really cut it anymore,
so when this happens, they may have surgery
to help deal with their symptoms,
and the goal of surgery is to inactivate
areas in the brain that are causing
their movement problems, like that shakiness
or stiffness that we talked about earlier.
This brings us to the long-term outlook
for someone with Parkinson's disease.
Unfortunately, Parkinson's disease is a progressive disease
so the disease will continue to develop
over the years after diagnosis is made.
While none of our current methods
are able to stop the disease,
medication and surgery can be really helpful
for managing the symptoms,
and making sure the person with Parkinson's disease
has a high quality of life for as long as possible.
I just want to mention a common misconception
that can crop up when we hear about Parkinson's disease,
which is that Parkinson's disease
only occurs in older people.
While it is true that the average age of diagnosis
is around 60 to 65,
about five to 10 percent of patients
are diagnosed before the age of 50.
This is often referred to as young
or early onset Parkinson's disease.
For patients with young Parkinson's disease,
those gene mutations we talked about earlier
seem to be the cause more often
than they are for patients diagnosed
in the average 60 to 65 year-old range.