One of the new studies is pretty remarkable because it claims to have achieved a first: making a fast-acting antidepressant. Prozac, one of the most popular pills on the market, takes about 14 days of continuous dosage in the system before it starts to alleviate low mood. The system proposed by the scientists in this study, from the University of California, seemed to do the same work in just eight days. If it can be applied to humans, it'd be a vast step forward.

The actual system they're proposing revolves around stopping an enzyme called glyoxalase 1, which normally hangs around helping to remove toxins that happen naturally in our bodies as our metabolisms create energy. If you stop it working, however, it seems to have effects on mood. We already knew that inhibiting glyoxalase 1 can reduce anxiety, but the new science out of California suggests that it can reduce depression too, and rapidly. The mice subjected to the tests showed a swift reduction in depressive symptoms, but there's a stumbling block: glyoxalase 1 inhibitors are expensive and not yet fit for human consumption on a wide, regular scale. (One retails at $250 for 10mg.)

Fortunately, the California scientists have filed a patent for an experimental drug that knocks out glyoxalase 1 (hopefully without the giant price tag), and they seem pretty positive about its chances for reducing depressive symptoms in humans.

If you're squeamish about surgery, it's a good idea to skip this section entirely. A huge issue for depression scientists — and for patients — is the phenomenon of entirely treatment-resistant depression, in which sufferers show no response to any of the myriad current therapies on the market (antidepressants of several classes, therapy, even electroconvulsive therapy, which is only prescribed in extremely severe cases). Treating depression that severe would be a massive boon and also highly marketable, and a new long-term study out of the University of Freiburg gives the first indications of a particular surgical intervention that may be helpful: deep brain stimulation.

Deep brain stimulation, as the neurological surgery department at the University of Pittsburgh explains, "involves placing a thin metal electrode (about the diameter of a piece of spaghetti) into one of several possible brain targets and attaching it to a computerized pulse generator, which is implanted under the skin in the chest below the collarbone. All parts of the stimulator system are internal; there are no wires coming out through the skin." It's a serious intervention, currently used for epilepsy, Parkinson's disease, and Tourette's, and utilizes electrical impulses that attempt to stimulate different areas of the brain.

For such an intervention to be deemed acceptable, the depressive symptoms of a patient have to be pretty severe. Only eight people were part of the Freiburg study, which targeted the superolateral branch of the medial forebrain bundle, an area crucial for the brain's interpretation of pleasure and quality of life. However, they underwent it extensively, over four years, and had their symptoms measured every month during that time. Four had their symptoms dip below the threshold for clinical depression, and seven out of the eight saw significant responsiveness. We already knew that this type of treatment on that specific brain segment worked in the first week of a trial, and in 2015 another study concluded that there was an "urgent need" to explore the process further. This is the first step, and now the University of Freiburg is mounting a bigger study, with 50 patients over five years. If that works, one day treatment-resistant depression may not be so resistant.

This is an annoying discovery for me, as I hate yogurt, but I may just have to suck it up and get some (or just a probiotic), because science is increasingly backing a theory that a probiotic bacteria has a positive influence on mood. While we've known about the link between the bacteria, called Lactobacillus, and mood for a while — scientists in 2011 found that feeding it to mice changed the way they regulated their emotions — the new study from the University of Virginia explains why for the first time, and also provides hope that it may be a mechanism that works in both mice and humans.

The gut-brain connection isn't just something dreamt up by your hippie Aunt Dot. It turns out that the gut microbiome, the microorganisms that make up your digestive system, can have some pretty intriguing influences on mental processes and mood, a news flash so big that the New York Times did a feature on it in 2016. ("Can The Bacteria In Your Gut Explain Your Mood," it asked. The short answer is yes.) When it comes to depression, the specific mechanism of Lactobacillus appears to be to set off a chain reaction. The Virginia scientists were studying mice, and found that Lactobacillus bacteria were very vulnerable to stress and would vanish from the gut if the mouse experienced it, raising depression symptoms. Lactobacillus, it turns out, moderates the body's levels of kynurenine, which sounds like a bad Japanese anime villain, but is actually a metabolite closely linked to a bunch of illnesses and problems, from immune disorders to schizophrenia. The less Lactobacillus, the more kynurenine, and that's bad news for depression sufferers; it turns out that kynurenine diverts amino acids that could be used to produce serotonin away to do other things. It's like a problematic traffic cop, and it's getting its orders from a gut bacteria. Yes, the body is an exceptionally weird place.

The good thing about the study is that the scientists found that just one dose of Lactobacillus was enough to restore its levels in the gut and cause depressive symptoms to lower and disappear. And they're confident that will happen in people as well. So go get yourself some probiotics.