Polypharmacy was common in this relatively refractory group; the group with past ECT averaged 2.5 medications per subject, and the non-ECT group averaged 2. Although it is impossible to rule out medication effects, there were no systematic differences in treatment between the 2 groups that would have predicted the current pattern of results. The atypical antipsychotic clozapine is the psychotropic medication with the greatest amount of data to support a salutary effect on cognition, and equal numbers of patients from each group were receiving clozapine (4 per group). Because clozapine is generally reserved for patients with refractory BD, the equal number of patients receiving this agent in each group suggests a rough equivalence in the refractoriness of the patient samples, supporting the fact that there was no difference in the illness burden for the patient groups. No patients were treated with first-generation antipsychotic medications or with other highly anticholinergic medications (tricyclic medications, antiparkinsonian medications) at the time of assessment.