What is treatment-resistant depression?
Treatment-resistant depression (TRD) is typically defined as depression that has not responded adequately to at least two antidepressant trials of adequate dose and duration. It affects approximately 30% of people with depression — a significant portion of the millions of Americans with the condition.
Why depression may not respond
Common reasons include: inadequate medication trial (too low a dose, too short a duration), an unrecognized bipolar spectrum condition for which antidepressants alone are insufficient, co-occurring conditions like anxiety, PTSD, or substance use maintaining depression, medical causes (thyroid disorders, vitamin deficiencies), and psychosocial factors that require therapy alongside medication.
Evidence-based next steps
Augmentation strategies (adding lithium, atypical antipsychotics, or thyroid hormone) have strong evidence for TRD. Ketamine and esketamine show rapid antidepressant effects in TRD with 50-70% response rates. Transcranial Magnetic Stimulation (TMS) is FDA-cleared and has 50-60% response rates. Electroconvulsive Therapy (ECT) remains the most effective treatment for severe TRD with 70-80% response rates and an undeserved reputation based on outdated depictions.
ECT has been dramatically improved since its portrayal in "One Flew Over the Cuckoo's Nest." Modern ECT is administered under anesthesia, causes no pain, and memory side effects — while real — are typically mild and transient. For severe treatment-resistant depression, ECT is often the most effective option available.