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Why Are There No Biological Tests in Psychiatry?

The views expressed are those of the author and are not necessarily those of Scientific American.

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Part 5 of a 5-part series

By Allen Frances*

When the third edition of psychiatry’s manual of mental illness, the DSM-III, was published 30 years ago, there was great optimism it would soon be the willing victim of its own success, achieving a kind of planned obsolescence. Surely, the combining of a reasonably reliable system of descriptive diagnosis with the revolutionary new tools of neuroscience would quickly yield a deep and broad understanding of psychopathology. And just as surely this would translate into standardized biological tests that would replace the cookbook listing of subjective symptoms and subjectively evaluated behaviors that comprised the DSM-III criteria sets.

Blood tests cannot yet reveal mental illness. Courtesy of Bobjgalindo via Wikimedia Commons

Sadly, progress has been much slower than anyone expected, with many exciting findings turning out to be no more than dead ends. The vast research funding has indeed provided a basic science revolution, but so far its discoveries have had no impact whatever on clinical diagnosis. Even the most promising candidates—biological tests for the accurate diagnosis of dementia—are several years away. And, for the rest of psychiatry, there is no immediate prospect that our rich basic science knowledge base and powerful investigative tools will contribute to clinical practice any time soon.

We have learned a great deal in the past 30 years, but perhaps the most important lesson is that the brain is ineluctably complex and reveals its secrets only slowly and in very small packages. There has been no low hanging fruit. The expectation that there would be simple gene or neurotransmitter or circuitry explanations for schizophrenia or bipolar or obsessive-compulsive disorder has turned out to be naïve and illusory. The problem of teasing out heterogeneous clinical presentations in psychiatry is compounded by the fact that they also have heterogeneous underlying mechanisms. There will not be one pathway to schizophrenia; there may be dozens, perhaps hundreds. Biological tests that appear to be associated with schizophrenia are never useful for making the diagnosis because they always show more variability within the category than between categories. And seemingly intriguing findings usually don’t replicate.

That progress in psychiatric diagnosis is slow should perhaps occasion no surprise. In every branch of medicine, the translational step between basic to clinical science has been difficult. For example, the discovery of genetic correlates for breast cancer has been much more of a slog than originally anticipated, with each advance explaining only a very small portion of the variance. And psychiatry faces the most awesome of translational leaps: the brain is ever so much more complicated than any other body organ, wired with complex redundancies that will defy simple and sweeping explanations of how it generates symptoms and behaviors. For the foreseeable future, except for dementia, we must reconcile ourselves to the staying power of purely clinical diagnosis in psychiatry.

Fortunately, despite all its obvious limitations, the DSM system does the necessary everyday job of fostering clinical communication and providing the foundation for treatment planning and clinical research. Granted that psychiatric diagnosis and treatment are purely empirical rather than based on understanding of mechanism, but this is also true of almost all available medical treatments. The good news is that descriptive diagnosis, when done well, usually leads to psychiatric treatment that is effective and efficient.

b&w images of disturbed young woman

Courtesy of Alaina Abplanalp Photography via Flickr.

But we must also not minimize the grave practical problems and limitations associated with not having biological tests to identify psychiatric disorders. Most troubling is the fact that the overwhelming majority of prescriptions for psychotropic medicines are written by primary care physicians who often have little training in psychiatry; little time to perform an adequate diagnostic evaluation; a tendency to depend on tests rather than talking to patients; and too great a susceptibility to quick trigger diagnosis and poorly chosen pill solutions (fostered by aggressive and misleading drug company marketing). The lack of precise and easily available biological tests in psychiatry permits much loose diagnosing and cowboy prescribing.

And beyond this, a diagnostic system without objective tests is vulnerable to arbitrary changes that can do more harm than good. The furor over the draft of the upcoming edition of psychiatry’s diagnostic bible, the DSM-5, is caused by its radical expansion of the boundaries of psychiatry that will increase by tens of millions the number of people presumed to be suffering from mental disorders. This would be done based on fallible committee decisions, unsupported by solid scientific understanding. Seemingly small and weakly supported changes in the definition of mental disorders can have huge real world impacts, often with extremely harmful unintended consequences.

The safest and most realistic course is to recognize and respect the limitations of descriptive diagnosis. DSM-5 got off on the wrong track because it held the completely unrealizable ambition to provide a paradigm shift. Striving to do the undoable, the framers of the DSM-5 have encouraged recklessly innovative proposals well before their scientific foundation has been prepared.

In clinical psychiatry, as in the rest of medicine, modesty is the best policy and “Do no harm” is the most important injunction. Descriptive psychiatry can serve us well if we don’t stretch it beyond its realistic limits.

*Allen Frances, an emeritus professor of psychiatry at Duke University, chaired the task force for the DSM-IV.

Yesterday: I reflected on why mixed depression/anxiety could be real, despite concerns that everyone might have it.

Ingrid Wickelgren About the Author: Ingrid Wickelgren is an editor at Scientific American Mind, but this is her personal blog at which, at random intervals, she shares the latest reports, hearsay and speculation on the mind, brain and behavior. Follow on Twitter @iwickelgren.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. DNLee 11:27 am 05/11/2012

    My twitter feedback is all in a tizzy over this article. A few of my follows contend there are biology-based tests in psych. I’ll encourage them to leave comments.

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  2. 2. tmonk 12:45 pm 05/11/2012

    The same reason there is none for Parkinsons Disease.They are heterogenous illnesses, lumped together often obscuring what are called endophenotypes. I think that might answer your question.

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  3. 3. jgrosay 2:33 pm 05/11/2012

    They used saying that anything having an impact on mood, thoughts and behavior is an organic disease until proven that no organic disease is present, but the spectrum of “physical” conditions influencing the “psyche” is so wide that it can take months and thousands of dollars ruling out them all. For example, it was shown that patients with Alzheimer’s disease have a higher incidence of previous infection with bugs akin to the one of Lyme’s disease. There are psychiatric scales that do exam the subject and emit an score to qualify or not for a diagnosis, or to make the follow-up of the outcome of a “psychiatric” disease, but many of them are just categorizations of subjective assessments by the doctor as it can be for the quality of a painting, it’s good not to mix scales from one type with the others, if not, you risk being blamed with a non-existent disorder and have negative social and work consequences from it, others, such as the Rorschach’s test are so close to esoteric, that the inter-rater variability may make them unreliable. An inherent difficulty in psychiatric diagnosis and therapy it that it has an underlying inherent model of sanity, and unless things that grossly distort your functioning or well-being or that of others are present, everybody has a right to be as original as they like to. Some people had devoted time and money to have a training in a job, and will do everything to show they’re indispensable, and be paid huge amounts of money for practicing their hobby.

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  4. 4. DSArrowsmith 6:23 pm 05/11/2012

    There are no biological tests in psychiatry because once a somatic cause is found, the illness is no longer psychiatric. Mental illnesses are those disorders of mood, cognition, behavior, etc. without a known etiology. Once the biological basis of a psychiatric illness is discovered, the psychiatrist hands the patient over to the oncologist (e.g., brain tumor), endocrinologist (hyper/hypothyroid, pheochromocytoma), neurologist (temporal lobe epilepsy, progressive supranuclear palsy), infectious disease specialist (syphilis, Lyme, encephalitis). The list is endless.

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  5. 5. Jerzy v. 3.0. 7:53 pm 05/11/2012

    Naturally there exist biological tests in psychiatry!

    I leave to the readers to google which tests are used to tell that a mouse is depressive, paranoid or demented. They are rather curious.

    I again point that animal tests are needed – not because scientists need jobs, but because each and every test has potential to help a patient. Imagine what would happen if patients with suicidal tendencies received completely untested drugs out of the dark, and some would worsen their mood!

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  6. 6. m 7:02 am 05/12/2012

    OH please,

    All people that believe in god are pychos.

    That leaves 23% of the popluation that are possibly not.
    Of those a few (say 2%) will have a high intellect and realise without an adequate emotion chip that a capitalised world means more money is better ands the easiest way to get it is off other people. A larger percentage will follow these intellectual highs, lets call them then the 22percenters. Making rougly 25% of the normal population criminally inclined. Same percentage apply in the religious frame-work.

    There is no cure for being human and smart, and psychitrists are too stupid to realise this.

    What should be answered is why do people have inadequate emotion capabilities and why do capitalised systems care about the rest, when they all want more money.

    Well Id say perhaps only a handful are truly in charge of there emotional state, because we evolved from a very aggressive species…very very aggressive, that spent most of its existence surviving off the death and control of other species and other “people” in our species.

    TO sum up: We are who we evolved from, it be a while before we evolve from that.

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  7. 7. cccampbell38 9:47 am 05/12/2012

    “m”: To quote you, “We are who we evolved from”. I agree completely. We are chimpanzees. That’s unfortunate. Why couldn’t we have been Bobobos?

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  8. 8. Doc Bunny 12:17 pm 05/12/2012

    On the contrary, there is a longstanding tradition of Biological Testing in Psychiatry. They’re just all classified.

    -Dr. Bunny

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  9. 9. marclevesque 12:27 pm 05/12/2012

    “we evolved from a very aggressive species…very very aggressive”

    What do we know about forest ape other than they are the ancestors of humans, bonobos and chimpanzees? And even though humans can behave like some cousin chimpanzees do some of the time, human violent behaviour is nearly incidental in frequency and scope when compared to human cooperative and supportive behaviours.

    Moreover, the probability of violent behaviour is related to cultural belief and rises as physical or emotional distance between the perpetrators and their victims increases, but even though the possibility of violence does exits in humans, it does not mean we have to continue its nurturing and promotion or assume its inevitableness because some other animals do it sometimes.

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  10. 10. jtdwyer 1:37 pm 05/12/2012

    marclevesque – good points, but remember that humans and other apes most often even cooperate in their violent behaviors – organized violence is all the more effective!

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  11. 11. Conductit 9:18 pm 05/13/2012

    I think most the most interesting aspect of our foray into Neuroscience is just that; we haven’t discovered or unlocked a biological or chemical design to abnormal psychology. I’m only an undergraduate but as far as I can tell much of Schizophrenia and Dementia seem to be Cognitive, based in the realm of thought. I’ve seen several studies of intimate social therapy working on long term outlook and perception having a wonderful rehabilitating effect combined with certain low dose anti-psychotics. (which seem to create a more receptive attitude, especially in patients suffering from paranoia)

    I believe that Cognitive studies will become much more important, Cog. Neuroscience is the next generation of Psychology as far as I’m concerned. It’s important to have the chemical and biological understanding with the full grasp of Psychology models to create a full understanding of the Human mind.

    And more importantly, we may never truly understand. Subjective reality of the observer warps all observation, we can never remove our human element of perception.

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  12. 12. vage slang 5:45 am 05/14/2012

    Subjective reality is what observation is, it’s impossible to say anything
    about reality. Words or theories are always models and therefore never reality itsself.

    Maybe the interface to our brain isn’t so bad, it’s how we perceive ourselve and our subjective reality. I wonder if science can do a better job, the solution might not differ that much from how we already perceive it. It also might imply it’s emergent, and you can argue on which level to study the brain, that is molecular, cell or networks of cells for example.

    Then again, I’m no scientist. I’ll not go into the ‘very very, very agressive species’ part. It’s too hilarious.

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  13. 13. gmperkins 11:03 am 05/15/2012

    “If the brain were so simple we could understand it, we would be so simple we couldn’t.” – Watson, Lyall

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  14. 14. HubertB 6:30 pm 05/17/2012

    There are no biological tests in psychiatry and never will be, because as soon as a biological cause is discovered for a mental condition, it becomes a neurological disease.

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  15. 15. Michael M 6:41 pm 05/17/2012

    Some tests involving gene sequencing, neurotransmitter production, exploration of diet, might be indicated to support DSM symptom diagnosis; however, they are not the quick and easy methods of which Dr/Mr Frances is speaking.
    Some commentors who have taken exception to the essay may have missed his stress of the point that most psychiatric drugs are prescribed by MDs who are General Practitioners. Neither DSM-any edition, nor accurate diagnosis of described symptoms are easily understood without significant special training. GPs are quite overburdened in modern medical diagnosis techniques.

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  16. 16. DSArrowsmith 7:08 pm 05/21/2012

    HubertB: more than neurology! Those interested in this subject might enjoy The Lumber Room: Mental Illness in the House of Medicine, which investigates the distinction between mental illness and physical illness.

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  17. 17. portland17 7:45 pm 05/22/2012

    Frances states himself early in the article that “The problem of teasing out heterogeneous clinical presentations in psychiatry is compounded by the fact that they also have heterogeneous underlying mechanisms. There will not be one pathway to schizophrenia; there may be dozens, perhaps hundreds.” Well, if schizophrenia is so heterogeneous in mechanism, clearly, it’s not a disease entity and will never have a test for it! It’s like saying back pain is a disease entity and trying to come up with a back pain test. Well, silly, the only test is that your back hurts. The question of WHY it hurts is the real question of diagnosis.

    As of now, the DSM can’t even distinguish between people who are having normal reactions to life events and those who are in some way physically pathological. We certainly aren’t going to get any tests if we are testing a group of people who are heterogeneous and looking for some test that will show that all of them have the same pathology! That’s just dumb science.

    Of course, the real problem with the DSM is that it is not a set of disease criteria at all – it’s a set of social constructs that are elevated to disease status by vote of a committee. Take ADHD – are these kids “ill” by any common definition of the word? Or do they simply have a behavioral style that teachers find difficult or annoying? Interestingly, when ADHD kids are put in an open classroom setting, they are virtually indistinguishable from “normal” kids, even by trained professionals. So is the problem in the child? Or is it in the expectations we set for them? Would this same “diseased” child be viewed that way in a hunter-gatherer society where they were allowed to run around all day and learn to throw spears and hunt and build things with their hands?

    There will never be tests for psychological diseases, because they aren’t really diseases at all. There may be people who are depressed, anxious or psychotic BECAUSE of a disease, but that group will be identified with a real disease and receive real treatment. Psychiatry will always be left to clean up those misfits who have the temerity not to be happy and functional within the social status quo. It’s social control, not science, and always will be.

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  18. 18. endrun 5:40 pm 09/11/2013

    portland17, you are so correct that it is a pleasure to read your blog post. However there is a bit of unreality to it that I would like to identify:
    The assumption is made that all “real diseases” will “receive real treatment.” This presupposes a kind and level of infallibility on the part of the larger Physician population that in fact does not exist. Those of us with Celiac Sprue, Ulcerative Colitis, and other “real” diseases who were treated as mental cases for years can provide this testimony and quite adequately. Psychiatry will of course never follow the scientific method, and only perennially snipe on the edges of science while making a mockery out of the entire concept, practicing social control endlessly, endlessly justifying itself with its own rather large and grand delusions about itself–while, by the way, continuing the process of the wholesale destruction of the meaning of the founding document of the United States of America, quite particularly, within the United States of America.

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