In this TED-Ed lesson, Madhumita Murgia shows how chronic stress can affect brain size, its structure, and how it functions, right down to the level of your genes.
TED-Ed Lesson Transcript
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 it’s 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 that regulates behaviors like concentration, decision-making, judgement, and social interaction.
It also leads to fewer new brain cells being made in the hippocampus.