So, as usual, another one of our friends on Facebook has decided to link to something "denouncing the evils of the modern medical establishment", claiming that (among other things) there are no lab tests for mental disorders (presumably because apparently chemical imbalance is an urban legend).

I don't care so much about some of the other claims (frankly, if anybody is prescribing enough Ritalin to produce adverse effects they should have their license revoked), although they might be bonuses.

So, can you do a lab test for a mental disorder, and if not, what mitigating factors should be taken into account?

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    There isn't any lab test to detect missing limbs, too. That doesn't a doc can't tell that someone's leg isn't there...
    – T. Sar
    Feb 13, 2018 at 10:42
  • I believe that a number of mental disorders can be detected using an MRI to show different regions of the brain trigger or other unusual brain activity. Of course this is not at all cost effective to be used as a diagnosis criteria in general.
    – dsollen
    Feb 16, 2018 at 13:58
  • @dsollen any links? most of what i read says MRIs dont show much. "That patients receiving treatment of MDD often showed reduction in sACC volume suggests the usefulness of this parameter as an objective auxiliary means of diagnosis for MDD." - this leaves enough wiggle room for MRIs to not help at all. ncbi.nlm.nih.gov/pmc/articles/PMC3100220
    – daniel
    Feb 16, 2018 at 23:17

2 Answers 2


So, can you do a lab test for a mental disorder, and if not, what mitigating factors should be taken into account?

A mental disorder typically manifests as a behavioural or mood disorder.

See the Diagnosis of schizophrenia, for example: there isn't what you'd call a "lab test" to detect disorganized speech, disorganized behaviour, blunted affect, etc. -- these are behavioural (not neurochemical) symptoms/criteria.

OTOH a doctor can give a person some prescription medication and see whether their symptoms improve: that's a kind of test: does the medicine work, have the desired effect?

The principal claim in the rant you cited seems to be:

“There is no definition of a mental disorder. It’s bullshit. I mean, you just can’t define it.”

Well it is defined, for example by the DSM.

The rant is right about a lot of things:

  • Misdiagnosis is possible (e.g. several diseases may present as similar symptoms and require Differential diagnosis)
  • Skilled/experienced diagnosis is recommended (people aren't supposed to self-diagnose)
  • Doctors can't be sure in advance which drugs if any will have the desired effect: it's a bit of an experiment

Perhaps this answers your question.

Incidentally, I noticed this today.

When A Patient Presents With A Painful Red Toe

The three women had superficial frostbite. No laboratory test exists for frostbite as it is a clinical diagnosis.


Clinical diagnosis

A diagnosis made on the basis of medical signs and patient-reported symptoms, rather than diagnostic tests

I don't think one would want to argue that "frostbite" for example doesn't exist or is an urban legend, nor blame it on the medical establishment, merely because it's diagnosed clinically rather than in a lab.

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    The methods of psychiatric diagnostics typically include an interview and may include psychological tests, typically administered in the form of questionnaires, but may also include more practical tests, including memory tests. In one test patients have to remember and repeat a list of words. Such tests are used in laboratory settings, for example, in psychology laboratories. The DSM criteria are based on scientific observations of clinical case reports, medical registry studies, as well as controlled laboratory experiments.
    – noumenal
    Feb 13, 2018 at 20:18
  • @noumenal those tests still aren't signs, or lab tests. For example a patient could score low on purpose. Doing psychology in a laboratory doesn't make it a science.
    – daniel
    Feb 14, 2018 at 13:33
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    @daniel It seems to me that you are neither familiar with science nor psychology. Patients typically seek treatment themselves and it would be to their own disadvantage if they lied. In some mental disorders there is a propensity towards lying, but these people are unlikely to seek treatment.
    – noumenal
    Feb 14, 2018 at 14:38
  • @noumenal it seems to me like you are applying psychology in a pretty limited way. You have never heard of psychology being applied for something other than helping a patient? Never heard of someone faking a mental illness? abc.net.au/news/2018-02-13/…
    – daniel
    Feb 15, 2018 at 10:38
  • Frostbite has signs. Risky click of the day, tell me if the hands in this picture are owned by someone with a mental disorder or frostbite vangoghgallery.com/catalog/Drawing/952/Four-Hands.html
    – daniel
    Feb 15, 2018 at 11:40

There are no biological markers of any kind for any DSM defined disorders. See for example the official statement from the chair of the DSM-5 task force: http://www.madinamerica.com/2013/05/chair-of-dsm-5-task-force-admits-lack-of-validity/

David Kupfer, Chair of the DSM-5 Task Force, while defending the DSM as a useful diagnostic tool in a press release, concedes that

“biological and genetic markers that provide precise diagnoses that can be delivered with complete reliability and validity” are still “disappointingly distant. We’ve been telling patients for several decades that we are waiting for biomarkers. We’re still waiting.”

The popular mainstream theory is that the DSM describes "symptoms" of "diseases", but there is no scientific evidence of any kind to prove the existence of any underlying "disease" for any of the symptomologies described in the DSM.

In light of the fact that no lab test can be done, we need to be very careful with how we define or describe people as being "mentally ill." The DSM-defined disorders, when looked at more carefully, tend to be extremely subjective and laden with cultural values and prejudices about what constitutes proper behavior and proper modes of thinking or feeling. For this reason, we need to be much more careful about forcing people to take "treatments," and look more towards how to provide voluntary options for support and help to people who are suffering.

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    I think you exaggerate the quoted claim and you probably need to find a more significant reputable source for a claim as sweeping as "no biological markers of any kind".
    – matt_black
    Sep 18, 2014 at 20:28
  • Also explain what "there are symptoms but no disease" means.
    – ChrisW
    Sep 18, 2014 at 20:40
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    @ChrisW en.m.wikipedia.org/wiki/Medical_sign#Versus_symptoms He said '"symptoms" of "diseases", but there is no scientific evidence', so he is right, if you can find a way to accurately diagnose a DSM style disorder in an unconscious patient in a room let me know.
    – daniel
    Feb 14, 2018 at 13:25

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