The Role of Biological Tests in Psychiatric Diagnosis


"Psychiatric diagnosis is certainly imperfect -- but so is much of diagnosis throughout medicine. And whatever the current limitations, psychiatric diagnosis is useful and essential. There are no 'paradigm shifts possible til we learn a lot more. To imply otherwise is misleading and confusing to patients."

May has been a dispiriting month for psychiatry and a sad and worrying time for our patients. Three of the leading mental health organizations have squabbled among themselves-- promoting silly and competing "paradigm shifts" while ignoring the unmet needs of our patients.

The mischief started with DSM-5 and its rogues' gallery of untested diagnoses that turn everyday life problems into mental disorders. Per DSM-5, people who don't need help will often get it (to their detriment), while those desperately in need of help will continue to be shamefully neglected. And to crown the irony, APA gets to collect fat publishing profits for producing a manual that is both unnecessary and unsafe. 

Then, to compound the mess, the National Institute of Mental Health issued an inflammatory press release criticizing all of current psychiatry-- for being brainless and invalid. NIMH made it sound like psychiatric diagnosis without biological testing is worthless.

This was mindless. DSM-5 certainly deserves to be roasted, but the NIMH sneak attack was a unfair and inaccurate broadside against all of psychiatric practice. NIMH was trumpeting its new research agenda to support its  request to Congress for an expanded brain research budget (the only thing it really cares about). The statement failed to admit that NIMH won't possibly be able to deliver any real progress in clinical care in this decade (and perhaps for many more). NIMH was taking down current psychiatric diagnosis, but offering nothing in its place.
Then the British Psychological Society joined the silly season by also suggesting that we suddenly discard our current system of psychiatric diagnosis-- this time in favor of a psychosocial paradigm that would make obsolete the valuable (if limited) old timers like schizophrenia and bipolar disorder. Of course, no details were offered and indeed no new model of psychosocial diagnosis actually exists. A mirror image of NIMH wishful thinking about the future with no relevance to pressing present needs.     

To bring some wisdom and perspective to this whirlwind of silliness, I turned to Barney Carroll-- one of the great pioneers of biological psychiatry and perhaps the world's leading expert on the role of biological testing in psychiatry.

Dr Carroll writes: "Here is a recent quote from the Director of NIMH: 'The weakness (of DSM-5) is its lack of validity. Unlike our definitions of ischemic heart disease, lymphoma, or AIDS, the DSM diagnoses are based on a consensus about clusters of clinical symptoms, not any objective laboratory measure'.”

"After a few awkward days, the chair of DSM-5 issued this agreement: 'In the future, we hope to be able to identify disorders using biological and genetic markers that provide precise diagnoses that can be delivered with complete reliability and validity'.”

"Patients receiving services are left to wonder whether (currently unavailable) laboratory tests are essential to the validity of their psychiatric diagnoses and the value of their treatments? Is psychiatry lost now in the wilderness without them?"

"Having biological tests is not a precondition for recognizing clinical disorders. It would be great to have them, but much good diagnostic work can be done without tests and their lack is not unique to psychiatry. The availability of biological tests is neither necessary nor sufficient for good patient care."

"So many conditions in medicine are diagnosed without any conclusive diagnostic tests. Think migraine. Think multiple sclerosis. Think chronic pain. Indeed, clinical science correctly recognized many diseases long before laboratory tests came along for confirmatory diagnostic application. Think Parkinson’s disease, Huntington’s disease, epilepsy… it’s a long list."

"We need also to be clear that laboratory tests are not an automatic gold standard of evidence for validity. Indeed, in many medical specialties, indiscriminate screening with laboratory tests has caused more harm than good."

"Laboratory measures are the servants of clinical science, not the other way around. Most laboratory tests will helpfully revise diagnostic probabilities, rather than conclusively rule in or rule out a diagnosis. Clinical judgment must always be used in their interpretation."

"Disease constructs take form through iterative attention to signs, symptoms, course of illness, response to treatments, family history, and laboratory data. This process of convergent validation has given us an A-list of psychiatric diagnoses that are candidates for future biological tests: psychosis, mania, melancholia, obsessive-compulsive disorder, vascular depression, crippling anxiety, panic disorder, dementia, autism, delirium, catatonia, and more."

"The fact that we have not nailed the pathophysiology of these conditions does not invalidate the diagnoses. We knew about Huntington’s disease and correctly diagnosed it for 110 years before its genetic basis was discovered."

"Psychiatric diagnosis is certainly imperfect -- but so is much of diagnosis throughout medicine. And whatever the current limitations, psychiatric diagnosis is useful and essential. There are no 'paradigm shifts possible til we learn a lot more. To imply otherwise is misleading and confusing to patients."  

Thanks Barney for clearing the fog with your common sense and deep experience. I would have said just the same things, but no one would have any reason to believe them. Your words carry unique authority given your lifelong commitment to establishing biological tests in psychiatry.

The biological reductionism espoused by NIMH and DSM-5 is not only nave and wrong-- it is bad for patients. As Hippocrates said: 'It is more important to know the patient who has the disease than the disease the patient has." Knowing  a person will always go well beyond knowing the lab test result. A Bio-Psycho-Social model is essential in all of medicine, but especially in psychiatry.

The NIMH and DSM 5 are eagerly chasing the holy grail of biological reductionism. But the brain will reveal its elusive secrets only in very small packets and only with the passage of many decades. Don't look for home runs or walks- be satisfied with singles and be prepared for many strikeouts.

Using a polio analogy, the NIMH director once said that he wants his institute to develop vaccines, not iron lungs. His ambition is to understand the biological roots of mental illness and to root them out. I fear that focusing on an over promised golden age in the future takes our eye off the obvious needs of patients in the present.

The delivery of mental health services in the US trails far behind most of the rest of the developed world. We have one million psychiatric patients in prison, most of them for nuisance crimes committed because they did not receive adequate care or housing in the community.

The NIMH seems to be totally indifferent to their needs and does nothing to promote its cause. It silently allows our country to engage in a barbaric mismanagement of the mentally ill that was abandoned elsewhere two centuries ago. NIMH would do well to promise less for the future and instead deliver more in the present. And DSM-5 should not have added new and questionable disorders at the fuzzy boundary with normal that distract attention and pull resources away from the unmet needs of the really sick.

We need biological research to improve the care of patients in the future, but we shouldn't be so dazzled by the (over)promise of neuroscience that we callously neglect our patients who are suffering now.


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