RESISTANCE TO ANTIDEPRESSANT MEDICATIONS AND SHORT-TERM CLINICAL-RESPONSE TO ECT

Objective: Traditionally, it has been widely assumed that the likeliho od of response to ECT is independent of the adequacy of previous treat ment with antidepressant medications. However, recent research has rai sed the possibility that medication-resistant patients with depression have a poorer clinical ECT outcome than patients who have not failed previous adequate medication trials. Method: Medication resistance of 100 patients with primary, unipolar, nonpsychotic major depression was evaluated during the index episode with the Antidepressant Treatment History Form. Patients were recruited and treated with ECT at three si tes; standardized ECT and clinical assessment procedures were used. Cl inical outcome was assessed immediately and 1 week after completion of the ECT course. Results: Patients who previously had failed one or mo re adequate antidepressant medication trials were less likely to respo nd to subsequent ECT than patients not known to be medication resistan t. This finding held within each study site, whether clinical response was assessed categorically or in terms of the magnitude of symptomati c improvement and after the authors accounted for other potential pred ictors of clinical outcome. Resistance to heterocyclic antidepressants predicted poorer outcome after ECT, while resistance to selective ser otonin reuptake inhibitors and monoamine oxidase inhibitors did not sh ow significant predictive relations. Conclusions: While a substantial percentage of medication-resistant patients respond to ECT, clinical o utcome in this group is inferior to that of patients without establish ed medication resistance. The predictive power of medication resistanc e is generalizable across diverse clinical settings, particularly for heterocyclic antidepressants, which perhaps suggests an overlap in the mechanisms of actions of ECT and this medication class.