High exposure to pharmacological treatments is associated with limited efficacy of electroconvulsive therapy in bipolar depression

Episode chronicity and medication failure are considered robust predictors of poor response to electroconvulsive therapy (ECT). In this study we explored the associations between indexes of drug exposure during current episode and outcomes of ECT in 168 bipolar depressive patients. The association between response or remission and number of previous pharmacological trials, failure of treatment with antidepressants, antipsychotics or combinations, and sum of maximum Antidepressant Treatment History Form (ATHF) scores obtained in each pharmacological class were tested. 98 patients (58%) were considered responders and 21 remitters (13%). Number of trials, number of adequate trials, ATHF sum, antidepressant-antipsychotic combination therapy failure and failure of two adequate trials were significantly negatively associated with remission. The association with ATHF sum stayed significant when controlling for episode duration and manic symptoms and survived stepwise model selection. No significant associations with response were identified. In conclusion, a history of multiple drug treatments may be linked to a greater resistance to all types of therapies, including ECT. However, we could not exclude that, at least in some patients, a prolonged exposure to pharmacological treatments may be responsible for a greater chronicity and for the presence of residual symptoms, which would explain reduced remission after ECT.