PLAT and hyperhomocysteinemia: In rats, tPA activity rapidly increases by over 50% after electroconvulsive shock, and remains elevated for more than 24 h.80 tPA mediates a variety of chemical reactions underlying the mechanism of action of electroconvulsive therapy.81 We recommend that patients refractory to the procedure be screened for conditions affecting tPA activity, such as hyperhomocysteinemia or antiphospholipid antibodies (Figure 1).