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Guest Blog: Biological Markers for Mental Illness

By: Vincent M. Wales

I am a person who lives with mental illness. I’m also a bit of a science geek. And I’m a writer, which means I’m also a researcher, by necessity. Put these all together, and you end up with a guy who likes to keep up with the science of mental illness – the causes, the symptoms, the treatments.

I’m also a person who is frustrated by the stigma surrounding mental illness and infuriated by those who deny that it exists. There are those who claim it’s all an invention by “Big Pharma” to make money, yet these people seem to forget that mental illness has been studied for much longer than “Big Pharma” has been around. There are those – entire organizations, in fact – who declare that all diagnoses of mental illness are spurious, because there’s nothing scientific to back them up, that there are no “biological markers” for mental illness as there are for “real” diseases. It’s this latter assertion that I’d like to address and, in my humble opinion, deflate.

What Is a Biological Marker?

So just what is a biological marker? In a nutshell, it’s when a simple test result indicates a particular problem in the body. For example, a blood test that reveals high levels of glucose is a fair indicator of diabetes. Diabetes is, of course, the result of a faulty pancreas. It’s the job of the pancreas to control blood glucose levels, so if it isn’t working properly, our blood sugar is high, as revealed by the test. The same is true for other tests that reveal problems with organs. Big change in your creatinine levels? Sounds like a kidney issue. High troponin levels? You’ve probably had a myocardial infarction. Those detected chemicals are biological markers.

Do these chemical markers exist for mental illnesses? Not that we’ve conclusively seen, so far. But this isn’t terribly surprising. Why? Well, look at those conditions listed above. We can detect problems with the pancreas because when it fails to do its job properly, the result is pretty clearly seen in high blood sugar content. But what is the brain’s job?

One can argue, of course, that the brain’s job is “everything.” But like any good manager, it delegates certain responsibilities (such as regulation of blood glucose) to other organs. When you remove all of those delegates, what remains? Thoughts. Emotions. Reasoning. These are not things that result in chemical markers, so – again – it’s not a shock that we haven’t found a chemical marker from when the brain is malfunctioning. It makes no sense to dismiss mental illnesses as imaginary just because we can’t detect it with a test of bodily fluids.

Other Biological Markers

But there are other biological markers beyond chemicals in our blood or urine. They are active readings, rather than passive. How do we know if we have hypertension? You don’t detect it from a drop of blood, but by measuring the pressure exerted by the blood pumping through your vessels. A blood pressure reading is a type of biological marker. Other such markers can be brain scans such as electroencephalography (EEG), positron emission tomography (PET), or magnetic resonance imaging (MRI).

Biological Markers of Mental Illness

So can we detect and/or diagnose mental illnesses from brain scans? Well, yes and no. It’s a murky area, primarily because the brain is quite obviously the most complex organ in the body (its job is “everything,” remember), and our understanding of it is in its infancy. If a person has a single mental illness, one that is well established, it’s likely that a scan can show this. However, if the illness is in its early stages, the scan will not be any help. More problematic, though, is if a person has co-occurring mental disorders. Simply put, we’re just not savvy enough yet to distinguish A from B when it comes to this situation.

What can we see? Brain scans of an individual experiencing a panic attack will clearly show hyperactivity in the amygdala, for example. This is logical, since we know that the amygdala is the “fear center” of the brain. But as those with anxiety/panic disorders know, sometimes there’s no external trigger, no reason to be afraid. Sometimes they’re sneak attacks. What that indicates is that the amygdala isn’t working as it should. The good news is that the panic attack can be seen in a scan. The bad news is that, once it’s over, the scan shows no evidence of it.

What about mental illnesses that are constant, not periodic as panic attacks are? What about depression? There are some well-known attributes associated with depression, including literal shrinkage of certain parts of the brain. Problem is, depression isn’t the only cause of such atrophy; chronic pain can do it, too. Such is the case with other attributes – a clear association, but not one that can be pinpointed as a true indicator.

It’s Complicated

Again, the brain is the most complex organ in the body, and even its different components, we’re learning, have more functions that we’d previously guessed. Like most medical things, it’s complicated, to put it lightly. But we are making progress on discovering definitive markers. It will be a long process, but I have little doubt that we’ll get there.

Today’s deniers of mental illness sound to me like those who ridiculed the germ theory of disease simply because they couldn’t see the germs, even though science pointed to the existence of such organisms. The same is true for mental illness. Just because we can’t yet detect the biological markers and show the physical causes of these disorders doesn’t mean that they aren’t there. One day, we’ll see them.


Don’t Call My Crazy is Gabe Howard’s Blog. He’ll be back next week. You can find him on his website,

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Guest Blog: Biological Markers for Mental Illness

Gabe Howard

Gabe Howard is an award-winning writer, speaker, and host of The Psych Central Show podcast who lives with bipolar and anxiety disorders. Gabe runs an online Facebook community, The Positive Depression/Bipolar Happy Place, and invites you to join. To work with Gabe or learn more about him, please visit his website,

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APA Reference
Howard, G. (2016). Guest Blog: Biological Markers for Mental Illness. Psych Central. Retrieved on June 6, 2020, from


Last updated: 12 Mar 2016
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