How stress affects your brain - Madhumita Murgia
Are you sleeping restlessly,
feeling irritable or moody,
forgetting little things,
and feeling overwhelmed and isolated?
Don't worry. We've all been there.
You're probably just stressed out.
Stress isn't always a bad thing.
It can be handy for a burst of extra
energy and focus,
like when you're playing
a competitive sport,
or have to speak in public.
But when its continuous,
the kind most of us face day in
and day out,
it actually begins to change your brain.
Chronic stress,
like being overworked
or having arguments at home,
can affect brain size,
its structure,
and how it functions,
right down to the level of your genes.
Stress begins with something called
the hypothalamus pituitary
adrenal axis,
a series of interactions
between endocrine glands in the brain
and on the kidney,
which controls
your body's reaction to stress.
When your brain detects
a stressful situation,
your HPA axis is instantly activated
and releases a hormone called cortisol,
which primes your body for instant action.
But high levels of cortisol
over long periods of time
wreak havoc on your brain.
For example, chronic stress increases
the activity level
and number of neural connections
in the amygdala,
your brain's fear center.
And as levels of cortisol rise,
electric signals in your hippocampus,
the part of the brain associated with
learning, memories, and stress control,
deteriorate.
The hippocampus also inhibits
the activity of the HPA axis,
so when it weakens,
so does your ability
to control your stress.
That's not all, though.
Cortisol can literally cause your brain
to shrink in size.
Too much of it results in the loss
of synaptic connections between neurons
and the shrinking
of your prefrontal cortex,
the part of your brain the regulates
behaviors like concentration,
decision-making,
judgement,
and social interaction.
It also leads to fewer new brain cells
being made in the hippocampus.
This means chronic stress
might make it harder for you to learn
and remember things,
and also set the stage for more serious
mental problems,
like depression
and eventually Alzheimer's disease.
The effects of stress may filter
right down to your brain's DNA.
An experiment showed
that the amount of nurturing
a mother rat provides its newborn baby
plays a part in determining how that baby
responds to stress later in life.
The pups of nurturing moms turned out
less sensitive to stress
because their brains developed
more cortisol receptors,
which stick to cortisol
and dampen the stress response.
The pups of negligent moms
had the opposite outcome,
and so became more sensitive to stress
throughout life.
These are considered epigenetic changes,
meaning that they effect
which genes are expressed
without directly changing
the genetic code.
And these changes can be reversed
if the moms are swapped.
But there's a surprising result.
The epigenetic changes caused by
one single mother rat
were passed down to many generations
of rats after her.
In other words, the results
of these actions were inheritable.
It's not all bad news, though.
There are many ways to reverse
what cortisol does to your stressed brain.
The most powerful weapons are exercise
and meditation,
which involves breathing deeply
and being aware
and focused on your surroundings.
Both of these activities
decrease your stress
and increase the size of the hippocampus,
thereby improving your memory.
So don't feel defeated
by the pressures of daily life.
Get in control of your stress
before it takes control of you.
