The Hyperbole of Blood Tests & Biomarkers for Depression
Mainstream media love to highlight anytime a researcher suggests we’re on the cusp of developing a blood test, saliva test, or brain scan to “properly” diagnose depression. This is seemingly driven by a never-ending belief that the only way to legitimize mental illness is if we create a medical lab test for it. Nevermind the fact that there are dozens (if not hundreds) of medical diseases that have no single lab test to diagnose them.
Somehow, an MRI will magically make depression acceptable to society. Nothing could be further from the truth.
The latest twist on these tests is a biomarker or blood test that will let us know which treatments may work best for depression. Naturally, such tests raise as many questions as they may answer — and make the process of getting an accurate diagnosis for depression vastly more expensive and complicated.
Mental illness is as much a subjective experience as it is an objective disease. It’s a false dichotomy to suggest that it must be one or the other. Its corollary — that only an objective biomarker could prove such a disease exists — must also be seen as just as ridiculous. While I respect researchers working in these fields, the implications of such research could de-value and harm millions of people who experience depression.
The New York Times’ Richard Friedman, MD shares the latest twist on this old story — using brain scans or blood tests to help dictate treatment:
Dr. Helen Mayberg, a professor of psychiatry at Emory University, recently published a study in JAMA Psychiatry that identified a potential biomarker in the brain that could predict whether a depressed patient would respond better to psychotherapy or antidepressant medication.
Using PET scans, she randomized a group of depressed patients to either 12 weeks of treatment with the S.S.R.I. antidepressant Lexapro or to cognitive behavior therapy, which teaches patients to correct their negative and distorted thinking. […]
Patients who had low activity in a brain region called the anterior insula measured before treatment responded quite well to C.B.T. but poorly to Lexapro; conversely, those with high activity in this region had an excellent response to Lexapro, but did poorly with C.B.T.
Sadly, just like the claim that a simple blood test for depression has been found (and then thoroughly debunked by James Coyne, Ph.D. over at PLoS’s Mind the Brain), this study shares similar and serious limitations with other research in this field. To hold it up as an example of what’s to come is clearly jumping the gun.
Worse yet is this doctor’s belief that an MRI or PET scan — and its analysis — is quicker than our current diagnostic methods:
One day soon, we may be able to quickly scan a patient with an M.R.I. or PET, check the brain activity “fingerprint” and select an antidepressant or psychotherapy accordingly.
When has a patient who isn’t in an emergency room ever experienced a “quick” MRI or PET scan? These kinds of scans need to be scheduled in a facility that has one of these machines — usually a hospital. It could be one or two weeks — depending upon the patient’s location and type of scan needed — before a patient gets in to be scanned. It could be another week (or two) before the results are analyzed and sent to the referring doctor or therapist. And somebody’s going to have to pay for all of these extra professionals and use of machines. None of this magically changes the existing health care system or infrastructure just because you’re looking for depression.
This kind of hyperbole sees technology as the solution to all problems, and ignores the stark reality of technology in the health care field today.
And how does it make a person feel if a brain scan puts them in one treatment group only for them not to respond to it anyway (since no test is going to be anywhere close to 100 percent accurate)? They went through all of that additional trouble and expense only to be back at square one a month later feeling even worse because the test was a false positive.
But then New York Times article oddly switches gears and acknowledges that simply getting a good patient history from someone who is depressed may also do wonders in helping us understand what treatments work best for them:
For example, there is intriguing evidence that depressed patients who have a history of childhood trauma, such as the early loss of a parent or sexual or physical abuse, do not respond as well to an antidepressant as they do to psychotherapy.
Indeed. As I wrote two years ago here:
But more importantly, all depression has biological underpinnings, social underpinnings, and psychological underpinnings. To try to separate these out into gross categories is to oversimplify this complex disorder.
It’s reductionist and harmful to people with mental illness to ever try and simplify their disorder down to a single cause — biomarker or otherwise — because it rarely captures the complexity of humans. And for those people who suffer from depression yet don’t screen positively on such tests? What will become of them?
For further reading
To Treat Depression, Drugs or Therapy? (NY Times)
Grohol, J. (2018). The Hyperbole of Blood Tests & Biomarkers for Depression. Psych Central. Retrieved on August 3, 2020, from https://psychcentral.com/blog/the-hyperbole-of-blood-tests-biomarkers-for-depression/