It’s clear that ECT affects short-term memory. If you think of your brain as a computer, ECT can erase anything that you haven’t yet saved to your hard disk. Some people can’t remember events from the day of each treatment. Some people lose memory for the previous few days. For people receiving ECT treatments two or three times a week, that can mean remembering very little of the whole treatment.
It’s less clear if ECT causes ongoing memory problems. To continue the computer anaology, the question is whether ECT damages your hard disk so you can’t save information in the future. Most research says that ECT doesn’t cause long-term memory problems. But some people do describe long-term problems with memory after ECT.
Concerns about risks of ECT (memory problems or other risks of anesthesia) were a major motivation to develop alternative treatments. These alternatives – transcranial magnetic stimulation (TMS) and vagus nerve stimulation (VNS) – were hoped to have the effectiveness of ECT without the risks or side effects. Both TMS and VNS have both been approved for treatment of major depression that does not improve with standard antidepressant medications. But it is not clear that either VNS or TMS is as effective as ECT for severe depression that has not responded to treatment with several medications. For the most severe and treatment-resistant depression, ECT still has the strongest evidence for effectiveness.