Treatment-resistant depression (TRD) is a form of major depressive disorder (MDD) where patients do not respond adequately to at least two different antidepressant medications, despite taking them at the proper dosage and duration. This condition affects about 30% of individuals diagnosed with MDD. TRD can be challenging to manage, but several therapeutic options are available, including medications, psychotherapy, and procedures like electroconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS).