New science has boosted the prospect that one day, we may have an easy test to determine whether your antidepressants are working — and it just involves eating sour foods. It's increasingly clear that there's a big link between serotonin levels and how well we taste sour foods, and medicine is contemplating how to make that into a full-blown test for depression sufferers adjusting their medicines or dosages. But we're not there yet, and the science may not be as helpful as it first appears. Which is unfortunate, since this is actually a really important issue.
Antidepressant suitability is a big problem for people with depression who are on medication. There are many antidepressant different options, from SSRIs (selective serotonin reuptake inhibitors) to tricyclics and atypicals; you need to have at least a spare half hour to understand the full range in all its glory. Tailoring depressive treatment to each person is an ongoing process for every person; every depressive person I know has had to adjust dosage or medication at least once in the course of their treatment, as side effects pop up or drugs cease to do their jobs properly. And we can't prod the brain to see if it's doing what it's supposed to. If there were an easy way to test if a drug is working on the neurological level, it would be snapped up immediately.
And it looks, tentatively, as if those days might be coming, but don't go out and set up a range of pickles and olives to taste test juuust yet. There are good reasons to hold back, too. Here's what you need to know.
The Connection Between Serotonin And Your Tongue
The first really big hint that serotonin levels in particular could be tracked via your tongue appeared in 2006. A research team at the University of Bristol gave healthy volunteers (who were not suffering from depression; remember that, it'll be important later) antidepressants, specifically SSRIs and NARIs, or noradrenaline reuptake inhibitors. They then checked how well the volunteers could detect specific "kinds" of taste, and discovered something very interesting indeed: anti-depressants helped taste. A lot.
On the antidepressants, their subjects could pick up on sweet and bitter-sour flavors at far lower concentrations than when they were on placebos. The volunteers on SSRIs could detect bitter tastes at 53 percent lower concentrations than they could before. Their tongues had been supercharged. What the hell was going on?
The key lies in what the antidepressants were actually doing. Both serotonin and noradrenaline are neurotransmitters; they're chemicals that transfer impulses from one nerve cell to another. And it turns out that both neurotransmitters are involved with how our brain processes different kinds of taste. The more of them, the better the mechanism was — but we didn't know how it worked until just this month.
How An SSRI Boosts Bitter Tastes
The relationship between serotonin and types of taste was cleared up a bit more in a study from the University Of Colorado School Of Medicine. They found, using mice, that that there's a specific type of taste cell in the tastebud (the one that busies itself with sour and bitter tastes) that uses serotonin to distribute its message to nerve cells. It's effectively acting as the signal that goes "yes, yeesh, this is bitter as hell, spit it out immediately, you weirdo".
So theoretically, if your SSRI is working on you like it should, it should make you more capable of tasting bitterness in the mouth, because it's blocking serotonin from being taken up, leaving more to mill around in the brain, boost mood, and help our bitter-focused taste cells. It's likely that noradrenaline operates in much the same way. But is this actually going to work in practice?
Why You Can't Exactly Taste Test Your Anti-Depressants Just Yet
Remember earlier, when I told you to take note of the fact that the study in 2006 was only done on healthy, non-depressed volunteers? Yep. That's a major obstacle to testing antidepressant success using a plate of bitter foods: nobody's yet published anything trying this technique out on people actually suffering from depression. That means we really don't have any clues about whether it would really work, or if depression alters taste in ways that mean a taste test for serotonin levels wouldn't work.
We're increasingly discovering that taste and depression have an interesting, and possibly complicated, relationship. People who complain that "food just doesn't taste good any more" after being dumped may actually not be exaggerating for effect; it seems pretty possible that depression and anxiety actually impair taste function. We're just beginning to understand it, though. A 2013 study found that serious stress alters how people detect glucose and salt in food, and a few studies have looked at whether depression, weight gain, and a diminished ability to detect sucrose might be related. But we're really at the beginning of this story, not at the end.
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