- How we conceptualize depression
has changed in the past decade.
In 2019, what do we think causes it?
That's what I'm talking about today.
I'm Dr. Tracey Marks, a psychiatrist, and this channel
is about mental health education and self-improvement.
If you don't want to miss a video,
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The traditional way we approached
the cause and treatment of depression
was to see it as a chemical imbalance.
That is, you have insufficient amounts
of the neurotransmitters serotonin,
norepinephrine and dopamine.
And low levels of these brain chemicals
are what was causing your depression.
We treat the depression by replenishing these chemicals
using antidepressant medications
that help the brain cells, or the neurons,
either produce more of the chemicals
or stop the chemicals from being broken down
after they're produced so that they hang around
a little bit longer.
And that's the concept behind the SSRIs,
or the serotonin reuptake inhibitors.
That concept is now so 2000.
It's not that we don't believe
that these brain chemicals are imbalanced.
It's just that as research has advanced,
we have a different understanding
of how they become imbalanced.
And the studies that support this
use functional MRIs, genetic biomarkers,
dissecting the brains of deceased people,
called post-mortem studies,
and looking at the brains of mice.
Mice, like other animals, get depressed too.
I'm telling you this in case you are someone
who wants to know what's the proof of this.
And I have references in the description,
and look at the Method section to see
how they measure the neurotransmitter levels
and how they detected changes in the neurons.
So now we see depression as caused
by abnormal connections between the neurons,
and this involves the concept of neuroplasticity.
When cells don't connect properly,
you get abnormal production of the brain chemicals.
- What?
- Hold on; stick with me here.
Neuroplasticity is the process of the brain
remodeling itself over time
as we learn new things.
Think of your brain as like
your computer's central processing unit
that functions through a complex circuit.
The circuit is made up of neurons
which are nerve cells.
As you learn new things,
new circuit paths are formed
and old, unused paths disappear.
These paths are just simply the nerve cells
connecting to one another.
The cells communicate by secreting chemicals.
These neurotransmitters become the way
that the cells transmit information.
Donald Hebb was a psychologist who developed
the theory called Hebbian theory
of how nerve cells function in the brain.
A catchphrase of his theory is
that neurons that fire together wire together,
and neurons that fire out of sync fail to link.
So how does this relate to depression?
With depression, there's a disconnect
between certain neural circuits.
And these circuits, by the way,
are mostly in the prefrontal cortex and your hippocampus.
And these are the areas of the brain
that regulate mood and information processing.
So instead of the neurons firing together,
the circuit chain is broken
and you don't get the transmission of the chemicals.
It's like negative neuroplasticity.
The circuit link is broken,
and this is where you get the inadequate amounts
of serotonin, norepinephrine and dopamine.
So this is what we see happening,
but we don't know exactly what makes this happen.
But we do believe that there is
more of an environmental influence
like stressful life events that makes it happen.
So it's not just due to something inborn.
What happens to you as you go along your life
can disrupt these circuits.
Why should you care about this?
Because it affects how we treat depression in the future.
Our current antidepressant medications are good,
but according to the STAR*D Study,
which was a sentinel study funded
by the National Institute of Mental Health,
a third of people did not respond
to multiple medication trials.
So treatment-resistant depression is a big problem.
So when it comes to treating depression,
we're missin' somethin'.
Even in the comments on this channel,
I see many people talk about how they took medication
for years with no success.
So now the newer drugs being studied
address preventing the disruption of the circuits.
And this focus actually addresses the problem
instead of the consequence.
Low serotonin is the consequence, not the cause.
It's like having a bleeding wound.
You can get something to replace the blood
that you've lost,
or you can close up the wound
that's causing the bleeding.
The new medication focus is closing the wound
instead of replacing the blood.
And we hope this new focus is better.
But another way this is a big deal
is that we have a better understanding
of how the psychotherapies like mindfulness
really improve depression.
Mindfulness has been shown to enhance neuroplasticity
and improve the connections in the circuits.
So it's a non-medication option
that has real promise.
I'll have an upcoming video on the topic
of mindfulness and neuroplasticity, so stay tuned.
Thanks for watching.
Talk to me in the comments.
I love hearing from you.
And see you next time.
♪ I am what I am today 'cause I did it my way ♪
♪ Nothin' y'all can say ♪
♪ In this life or the next one ♪