- Imagine if a quick little blood test could help doctors diagnose depression - Determining if someone has depression can be surprisingly difficult, which is bad because depression is one of the biggest contributors to suicide and other life-threatening conditions like heart disease and diabetes - In the U.S., one in six adults will suffer from depression at some point in their lifetimes, and many will never get diagnosed.

- And that's a shame because depression is treatable and in some cases even preventable.

So why don't we have a biometric test that can detect depression?

- If you go to the doctor with a broken arm, you can get an x-ray that'll show the doctor exactly where the damage is, but you can't do this with mental health disorders like depression.

There are no scans or lab tests, you can't just walk in and get a biopsy of your brain that tells people exactly what's happening.

- Mental illnesses are diagnosed mostly from a patient's self-reported symptoms along with their behaviors.

Basically it boils down to how they say they feel.

But we know some people report less reliably than others because of things like stigma, shame, or cultural taboos - Compared to other physical diseases, depression is a trickier diagnosis to make.

It can be a little bit more subjective and vary from person to person.

- In psychiatry, up to now we've flying pretty blind.

The patient comes in and says, "I feel well, maybe I feel a little more stressed than usual."

And you ask a series of questions.

If you're very diligent, you might ask a family member how do you think your husband, or a son, or daughter, or spouse, or partner has been feeling and functioning?

So you could try to triangulate different perceptions of the person, but that's obviously not the same thing as objectively tapping their biological activity.

- Many of the symptoms of depression are the same as normal healthy feelings, but are different in how long they last.

So it can take a clinician a while to make a diagnosis.

- There are nine official symptoms of depression known clinically as major depressive disorder.

Let's say you check off five of these symptoms, they persist almost daily for two weeks, cause significant distress, and are not related to any other medical conditions.

Well there you go, you have clinical depression.

- This means you can have two patients diagnosed with depression, but only have one symptom in common.

Here's an example.

You can have an insomniac who is fatigued, can't concentrate, anxious, and feel sad all the time.

- And that person will have the same diagnosis as someone who sleeps too much, has lost joy in all activities, contemplates, dark thoughts feels worthless and has gained 30 pounds.

- And to make matters more complicated, if you have one mental health disorder, you are more likely to have another.

In the medical world we call this comorbidity, and it can leave your therapist wondering, does this patient have depression or maybe anxiety or maybe depression with anxiety-like characteristics.

And this whole diagnosis confusion Can mean that a patient isn't getting the best treatment.

- But what if along with checking for diabetes and cholesterol, you could also get a quick lab test that assess your mental health.

Well, that's where biomarkers come in.

- Biomarkers, make it possible to measure what's happening inside the body.

They can be proteins, genes, hormones, any molecule that can be used to trace a normal or abnormal condition or disease.

If you've ever gone to the drugstore to buy a pregnancy test, you're using the hormone human chorionic gonadotropin or hCG as a biomarker to detect pregnancy.

- And we use biomarkers all the time in medicine.

For example, if I wanna know if a patient's had previous heart damage, I'll order a troponin level to look for that.

But if you wanna develop a reliable test, then you need a biomarker that accurately reflects what's going on inside your body.

- So what inspired you to create an objective test for mental health?

- I was inspired in some measure by my work with law enforcement.

I helped the NYPD cope with the horrible losses they experienced at the time of the 9/11 Twin Towers attacks.

And what I realized in my work with law enforcement and the military is that for reasons, which I think are obvious, these are men and women who are very resourceful, very proud, very self reliant and very count on themselves to be able to perform highly and under very dangerous circumstances.

And so for them to acknowledge what we call the invisible wounds of war, which are traumatic stress, depression, traumatic brain injury and related problems, it's quite a blow to their self-esteem and may be very difficult for them, and they may be very fearful of damaging their career ambitions by acknowledging their own psychiatric limitations.

So we have to go beyond just asking them are they having depressive feelings, or anxious thoughts, or disturbing dreams of their experience and be able to really test objectively whether they're suffering from these invisible wounds.

- And having an accurate and reliable biomarker for depression may actually help us better understand the underlying cause, and strengthen mental health by making it more objective.

- For the people who are told it's all in their head, this could really validate their experience by having their condition taken seriously as a disease, because it is.

Some scientists are using functional MRI to peer into the brain.

What they're seeing is patterns of connectivity that align with a wide range of symptoms seen in depression - But the resolution is crude.

I mean, there can be a hundred thousand neurons in just a three millimeter cube sample area.

Another downside, they're pretty expensive and it's not like you can quickly get one done and then mail in a sample.

- This is why some researchers are looking at blood tests because it's cheap and doctors already know how to use them.

- When blood leaves the brain, it carries with it little pieces of RNA into the bloodstream.

And this is where they can be detected and measured by a blood test.

Researchers at Indiana University looked at thousands of possibilities that could be tied to mental illness and they narrowed it down to 13 potential biomarker that can be used to aid in the diagnosis of depression and other mental health disorders.

- We followed psychiatric patients when they were in a low mood, depressed state and in a high mood state over time.

And in the same person, you can see what changes in their blood from when they're depressed to when they're doing well to when they're doing better than well, when they're manic and so on.

So by having this trajectory of molecules that change in the blood in relationship to disease state and treatment, you're able to identify which of the thousands of things that changing the blood actually is a good tracker.

And that's the first step.

The second step is to look at the list of things that you found in the group of people you followed and say is there some additional evidence for them that would make them more likely to be reflective of a brain disease?

And then the third step is the validation step where you're going, people who are clinically sick, very sick and and see if your markers are changed even more over there.

And we do an additional fourth step where we look in clinical settings and see, can we predict who will have a hospitalization?

Can we predict who is depressed and so on just by looking at their blood samples?

We're very careful and methodical about making sure that we have all of our ducks in the row, that it's something that's real because we don't want to give sort of false hope to patients, their families and so on - These blood tests still need to be verified on a larger population so we know their true accuracy.

Although these tests add a new significant tool to the field, it's only a stepping stone to truly understanding depression as a disease.

- Currently, the accuracy of the blood test is about 65%.

But when you combine this with a full assessment of the patient, that number jumps up to 85% and that's comparable to tests we use every day.

For example, if you go and get your LDL cholesterol level checked, the accuracy of that test is 85%.

- So the test is available now but why haven't we seen it yet?

Because it's only available to physicians through an early access program.

And even though it's cheaper than an MRI or an unfortunate hospitalization due to an untreated mental health disorder, it's still very costly.

- I think not only would an objective marker de-stigmatized depression completely, it may also add to existing research, protocols.

maybe we'll get some more support from the private industry from insurance, and also maybe it'll be set treatment standards and say, Hey, if the patient meets these symptoms and has a biomarker level of X, then we need to start treating with Y.

- How will these biomarkers be used in the future?

They'll be used to take psychiatric disorders like depression, and PTSD, and panic disorder, and other schizophrenia, bipolar disorder and fractionate it into different distinct subtypes based on the biomarker profiles.

And then use that information to personalize and customize treatment.

So treatment will no longer be one-size-fits-all.

- It would be a sort of a big step for psychiatry, it would be a small step for medicine because all those things already being done in other specialties.

And we just need to develop similar approaches in mental health.

- If you have a unique story about being diagnosed for mental illness and you're comfortable sharing it, please do so in the comments.

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- [Announcer] If you or someone you know is struggling with depression, call the SAMHSA National Helpline or go online at www.samhsa.gov.

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