If you have ever read about ECT, you have probably seen the word "electrodes" and not much explanation of what that means in practice. It turns out the placement matters enormously.
This review looked at ECT for depression that has not responded to at least two different antidepressants. One of its clearest findings is that placing the electrodes on one side of the head only — called right unilateral placement — works about as well for major depression as placing them on both sides, but comes with fewer problems with thinking and memory afterwards.
That is a genuinely useful thing to know if ECT is being discussed for you or someone you love, because it is a question you can ask. Not every side effect is an unavoidable price of treatment; some depend on choices your treating team makes.
The review is honest about the limits of current knowledge too. Researchers have found changes in brain volume after ECT and some signals about who responds best, but exactly why ECT lifts depression is still not settled.
If depression has not shifted despite trying more than one medication, it is worth asking your GP or psychiatrist what options remain — there are usually more than people expect.