Breathtaking News for Depression and Schizophrenia

A simple breath test can distinguish depression and schizophrenia.

“As long as there's breath in our lungs our story is still being written.” –Bart Millard

A new study shows that two chemicals from breath samples, butyrate and trimethylamine, are sufficient to distinguish depression and schizophrenia with 80 percent accuracy. These chemicals are both produced by gut microbes. This implies that the correlation between gut microbes and these two mental conditions is surprisingly robust. If, in a room full of people with multiple mental issues, you can distinguish them by their microbes, then perhaps we should be paying more attention to these microbes.

For about two decades now, we have understood that there is an intimate connection between gut microbes and mental health. But many professionals in the psychiatric field have been reticent to incorporate this knowledge into their practice. They know they have some patients with gut issues, but they also have many who seem to be free of them.

However, the gut issue is often hidden and, thus, unlikely to be encountered in normal therapy. Some psychiatrists point out that drugs already help many of their patients. Why mess with something that’s working? If only a fraction of psych patients have obvious gut issues, is it really worth pursuing?

Reasons to look again

There are several problems with this attitude. One is that drugs don’t work for many, and we don’t know why. To complicate the issue, drugs interact with gut microbes. Drugs can kill some microbes and nourish others, which is rarely considered by doctors or the Food and Drug Administration. Microbes can also affect drugs by degrading them or converting them to other chemicals. Could these interactions with gut microbes explain the uneven effects of psychoactive drugs?

For many psychiatrists, this research seems fringe, but studies are finding that the gut-brain axis exerts more influence on mental health than previously appreciated. And, since psychiatric disorders are among the leading causes of disability in the world, the truth here is consequential.

This is not the first study to find such an important association between gut issues and depression. A Chinese study found that 70 percent of patients with depression had gastrointestinal (GI) symptoms. The worse the depression, the worse the GI problems. Coming from the other direction, about 80 percent of patients with irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD) also suffer from depression. These numbers imply that the gut-brain connection is much more important than we thought. Far from fringe, it may be a factor in the majority of psychiatric cases.

Correlation is not causation

Correlations are great, but they don’t show whether gut issues cause mental problems or the other way around. However, in this case, it may be enough to simply note the association. The gut-brain axis is really a cycle: We know that the brain can alter gut microbes and vice versa. It almost doesn’t matter which was the primary cause, because once the vicious cycle is set in motion, it can propagate on its own, a perpetual motion machine cranking out malaise.

This sounds pretty gloomy, but it actually offers hope. It means there are two levers to pull: Either change the brain or change the gut.

Twin interventions

On the brain side, intervention works surprisingly well. Intriguingly, cognitive behavioral therapy can improve our gut microbes even as it improves our mood. That unexpected outcome suggests that traditional psychiatry may have been working in concert with gut health all along.

On the gut side, intervention also bears fruit. Improving your gut microbiome to enhance brain function is the ultimate goal of the gut-brain connection. It aims to boost the populations of psychobiotics—microbes that can improve our mood. Our psychobiotic gut microbes love fiber, but, sadly, modern food manufacturers assiduously remove fiber in a quest to make ultra-palatable fast food. Replenishing fiber via veggies and berries can nourish the psychobiotic microbes in our gut, improving cognition, mood, and memory. Prebiotic and probiotic supplements may also help.

Psychobiotic microbes also relish fermented foods, like yogurt, kimchee, kefir, sauerkraut, and pickles. Ferments contain both beneficial microbes and the fiber they love in one package. This is an important part of the Mediterranean diet, which has been shown to improve overall health and mood.

This research is literally breathtaking. Adding a simple, noninvasive test like this to a psych workup would not be inappropriate. The results could help to guide future therapy.

In sum

There will be trauma in our lives, and therapy can help us deal with it. But fixing our gut can also help by making us more resilient to those stressors. Knowing that your gut is involved could even lead to smaller doses of psychoactive drugs, once the toxins in the gut have been addressed.

It seems crazy that microbes could affect our mood, cognition, and even our personality, but recent studies are building a strong case. As Hippocrates noted some 2,500 years ago, all illness starts in the gut. And the state of our gut is up to us.

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References

Henning, Daniush, Marian Lüno, Carina Jiang, Gabriela Meyer-Lotz, Christoph Hoeschen, and Thomas Frodl. “Gut–Brain Axis Volatile Organic Compounds Derived from Breath Distinguish between Schizophrenia and Major Depressive Disorder.” Journal of Psychiatry & Neuroscience : JPN 48, no. 2 (April 12, 2023): E117–25.

Jia, Huang, Cai Yiwen, Su Yousong, Zhang Ming, Shi Yifang, Zhu Na, Jin Feng, Peng Daihui, and Fang Yiru. “Gastrointestinal Symptoms During Depressive Episodes in 3256 Patients with Major Depressive Disorders: Findings from the NSSD.” Journal of Affective Disorders, February 17, 2021.