How Does That Work?
Think back to the last time you had the flu. You were probably lethargic, unable to concentrate, and generally uninterested in anything that didn't involve lying in bed waiting for your next sweet NyQuil dose. You might think it was flu virus itself causing this mental crappiness, but nope, it was your own body, the little bastard. When you're fighting an infection, stress, or anything else that the body thinks is bad for it, your immune system releases proteins called cytokines, some of which cause inflammation. The apathetic mood produced by these little cytokines is known as "sickness behavior," and it's no coincidence that it looks a lot like clinical depression -- among other things, pro-inflammatory cytokines lower serotonin levels, and low serotonin does not exactly equal kittens and rainbows.
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Not even kittens on rainbows could cheer this guy up.
On the surface, making you feel like crap mentally when you've already got sickness to deal with seems like a dick move on your immune system's part, but inflammation is a crucial part of fighting off infection and fixing damage to your body. The sickness behavior it brings with it can actually be an advantage; you're more likely to get better from the flu if you stay in bed and stare at the wall rather than go out to compete in a roller derby. The system only goes wrong when sickness behavior appears without an obvious illness or injury to cause it, and that's when things really start to get weird. There's a theory that a lot of what we call "depression" is actually sickness behavior caused by a source of inflammation that's hiding out in your body somewhere, messing the whole place up like a rotten burrito at the back of a fridge.
You'd expect that if some forms of depression were in fact long-term inflammation in disguise, medical treatments that supercharge the immune system (and therefore cause inflammation) would also cause depression. And you'd be right, smart person! The hepatitis C virus is sometimes treated with injections of a type of cytokine called interferon, which pumps up the patient's immune system. One in four previously non-depressed patients who undergo interferon therapy will develop a major episode of depression as a result of treatment, and some estimates are even higher than that. That's right: If you're lucky enough to be one of the people vulnerable to the psychological effects of a crazily boosted immune system, depression is injectable.
Do it for the Vine.
So if you're currently depressed, and the people around you keep brushing it off and telling you to toughen up, clearly the thing to do is carry an interferon-filled syringe around. The next time someone tells you that depression is "all in your head," jab them in the neck with your syringe and see how they like it.
C. Coville is not responsible for any assault charges that might come as a response to sticking a syringe into people's necks, but can be found on Twitter and Tumblr.