Today’s newsletter has a very important study about depression, learning, and improving your situation.
There is a very well known story about how they train fleas for a flea circus.
The type of fleas used in these circuses typically jump 8 to 12 inches.
Researchers put the fleas in a test tube, so that when the fleas jumped, they hit the top of the test tube. Ouch!
It hurt hitting the top of the test tube. Jump, ouch. Jump, ouch.
They continued to jump to the top, jump and hit the top, until after maybe an hour, they stop jumping because hitting the top hurt and they finally learned that it hurts to jump high.
And these fleas never jump high again.
So now they’ll stay in one place, which is perfect for a flea circus.
The fleas have what psychologists call, “learned helplessness.”
And learned helplessness isn’t the same as depression…
Learned helplessness is thought to be a different brain problem than depression.
In learned helplessness, a person does not try to escape from their situation, even if they can escape!
In depression, a person is essentially just stressed out.
They’re dealing with high levels of stress hormones, which cause a person to slow down, stop having initiative, think negative thoughts…
With that in mind, the question that these researchers in Japan decided to answer is this.
What effect does learned helplessness and stress (including depression) have on learning and memory?
What’s very clever about this experiment is the way that they used mice to answer this question.
And I am about 100% sure that the answers the mice provide are the same answers that people would provide — if similar experiments were ever done with people (which will never happen).
The researchers had three groups of mice — one group of mice was taught learned helplessness, one group was stressed out to mimic the effects of depression, and one group was the “control” group.
To teach the mice learned helplessness, they took the mice and gave them electric shocks that they could not escape from.
Not debilitating shocks, but very annoying shocks. They weren’t abusing these mice, but they were giving them annoying and unpleasant shocks that anyone would want to avoid.
But…and this is where the “learned helplessness” comes in — they did not let the mice escape the shocks!
After a while, these shocked mice learned that they could not escape the shocks.
And so even when the researchers gave these mice the means to escape, the mice still sat there and were shocked. They had learned that escape was impossible — they had learned helplessness.
These were the mice who learned helplessness– mice who took the punishment without trying to avoid it.
So let’s talk now about the second group of mice — the depressed mice.
To teach the mice depression, they gave them all sorts of stressors, such as tilting their cage at random intervals, depriving them of sleep, depriving them of food for short periods of time, and so on.
This is a very common accepted way to cause chronic stress in mice.
You can’t really say the mice were depressed, but you can certainly say that the mice were stressed out.
And the control group was not put through either of these processes.
Then they tested ALL the mice — the shocked mice who had learned helplessness, the stressed out and depressed mice, and the (lucky) control mice who were left to live normally.
The researchers gave all three groups of mice mazes and swimming tests.
And they discovered that the mice who had learned helplessness did very poorly on the maze and the swimming tests.
And the stressed out, depressed mice did badly on the maze and swimming tests, too.
The mice that hadn’t been given shocks or stressors, did much better on the maze and swim test.
Now the researchers gave all three groups of mice antidepressant medications in clinically significant quantity.
And because of the drug,
the learned helplessness and stressed mice got a lot better at the maze and swimming tests.
After the antidepressant had taken effect, the learned helplessness and stressed mice were able to perform almost as well as the control mice.
The researchers measured levels of two significant chemicals in the mouse bodies.
One chemical they measured is cortisol, which indicates stress in the body.
Cortisol was elevated in the stressed and learned helplessness mice, and when cortisol levels fell, the learned helplessness and stress mice learned and did a lot better in the maze and swim test.
As the researchers observe:
BRIEF PERIODS OF STRESS POTENTIATE MEMORY FORMATION, WHEREAS MORE SEVERE OR PROLONGED STRESS HAS DAMAGING EFFECTS UPON BROAD ASPECTS OF COGNITION.
The researchers also studied something called brain derived neurotrophic factor, or BDNF, which is thought to create additional brain cells.
BDNF helps the brain change itself, the phenomenon known as neuroplasticity.
The mice that have high BDNF learn quickly and perform well on the maze and swim test.
The mice that had learned helplessness or who were stressed, and who did not have the antidepressant medication, had much lower BDNF levels.
So the researchers neatly tie in stress, learned helplessness, stress hormones such as cortisol, and the learning chemical known as BDNF.
BDNF IS IMPLICATED IN SYNAPTIC PLASTICITY SUCH AS LONG-TERM POTENTIATION.
That means BDNF helps to increase learning and make the brain more easily rewire itself.
But high levels of stress, anxiety and learned helplessness KILL BDNF levels, and therefore interfere with learning.
So what should we take out of this research?
It’s essential that if you want to learn something, and you want to get better, you need to set things up in your environment to succeed rather than fail.
It’s very clear that both learned helplessness and chronic stress will interfere with your learning.
Learned helplessness and stress will cause your brain to virtually shut down its learning ability.
The solution may be antidepressant drugs, or it may be nutritional supplements that raise BDNF levels and lower your body’s cortisol and adrenaline levels.
There are nutritional approaches that raise BDNF and help the brain modify itself and rewire itself more quickly.
There’s no question that the answer lies in better nutrition, supplementation, and removing the learned helplessness and chronic stress in your life as best you can, situationally.
That means for human beings having control over their lives.
The feeling of being in control is essential to living long and living happy.
You can do all the nutrition and supplements and drugs in the world, but if you don’t feel like you’re in control, you’re going to be chronically stressed, and you’re probably not going to be thinking very clearly.
Citations
Impairment of the spatial learning and memory induced by learned helplessness and chronic mild stress
http://www.sciencedirect.com/science/article/pii/S0091305706000086
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