By Mark I. Levy, MD, DLFAPA
fpamed Forensic Psychiatrist

Not everyone with Major Depressive Disorder (MDD) responds to antidepressant medication. Researchers are increasingly asking “Why?” and coming up with novel understandings.

The most common antidepressants prescribed these days are close to a dozen different SSRIs (selective serotonin reuptake inhibitors, e.g., the Prozac family of drugs). What is especially interesting today when studying patients with symptoms of Major Depressive Disorder is addressing the question of why some patients are “non-responders” to the most commonly prescribed antidepressants, what used to be called “Prozac poopout.”.

An article from Psychiatric Times discussed a recent study of the gut microbiota (i.e, the normal gut bacteria) which clearly delineates a significant difference in the population of gut bacteria found in depressed individuals who respond to SSRI antidepressants compared to those who do not.

These emerging findings have a direct implication for civil litigation where emotional damages claims are alleged in which symptoms of chronic depression do not respond to or improve following appropriate treatment with standard antidepressant medications. Continued symptoms of depression despite antidepressant pharmacotherapy have traditionally been labeled “treatment resistant depression” and are often presented as evidence of the severity of the emotional damage sustained by a plaintiff after a loss or trauma. That conclusion, although appealing, may not be wholly accurate.  There are now a growing number of bio-markers available in modern psychiatry indicating which patients are likely to respond to specific treatments (including SSRI antidepressants) and who may be non-responders, not because their depression is more severe or  “untreatable” but because they are genetically or physiologically non-responders to specific treatments but should respond to others. They simply may require different treatment strategies due to their individual physiology. Such an enlightened approach may end the disabling chronicity of one person’s Major Depression in the same way that an SSRI anti-depressant resolves the disability of another.

Although there is much still to be learned about “biomarkers” and what they teach us about the pathophysiology of depression, today research is focused and accelerating in this area of psychiatric research known as “the search for biomarkers” for specific mental illness. Finding and understanding biomarkers for mental illness is inexorably linked to developing new and more effective treatments for depression since, even among patients with Major Depressive Disorder, it is no longer naively believed that “one shoe fits all.”