We all feel very educated about matters related to the brain. We know words that a few generations ago sounded like complicated medical jargon, and we drop them with ease in everyday conversation. When we feel joy, that’s a hit of dopamine. When we feel pumped, endorphins flood our systems. And when we feel blue, we say our serotonin levels have dipped. 

Don’t be so sure about that last part, though. Numerous studies have tried to see the effects of serotonin on depression, and there’s simply no convincing link between the two

The serotonin hypothesis goes back around 50 years. Doctors were trying to figure out what the deal with serotonin is, and they couldn’t just inject the stuff right into people (doing so wouldn’t raise brain serotonin; that separation’s called the “brain blood barrier”). They could however deprive people of a chemical needed to make serotonin, tryptophan, and when these subjects had been depressed before, robbing them of tryptophan made them depressed again.

That sounded like it meant something. And yet today, we have drugs that can raise patients’ serotonin levels instantly (not by giving them serotonin directly, but through other means). And these drugs have no instant effect on depression at all. They take weeks to work. 

So you need weeks of high serotonin to feel good then? No, say the scientists who review all the research. To explain why not, well, that requires a little more neurological knowledge than a layperson has, but it involves studying serotonin activity in addition to just serotonin presence, through a bunch of different factors, and the conclusion is that there’s just no link to be found.

Not that that means you should throw out those serotonin-boosting drugs. Because, see, those drugs do work ... they just appear to work through means independent from boosting serotonin. The drugs do multiple things. All drugs do multiple things. If nothing else, they work because placebos are remarkably effective at treating depression. 

So we have absolutely no medical advice to give you based on this serotonin info. Just general advice to be humble about how little related to the brain we really know. Don’t be surprised if our descendants put us roughly on par with people who believed in the four humors.

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For stories that won’t depress you, check out:

5 Mind-Blowing Ways Science Has Hacked the Human Body

Man Has Mystery Illness, Gains Super Memory and Painting Powers

Myth: Depression Is Just Brain Chemicals Making You Hate Your Otherwise Normal Life

Follow Ryan Menezes on Twitter for more stuff no one should see. 

Top image: Tom Varco

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