I had a talk with my step dad about ECT - just to get more information and perspective...
How I understand it now it that it causes a seizure (spelling??) similar to an epileptic fit. They apply an amount of elec. current (depending on the 'threshold' of your body/mind which is determinded prior). I guess if you think about the heart and brain as having electric currents - when your heart stops working they apply a current to get it started again.. well the ECT is similar.
From my step dad's experience it works best with Major Depression (when the underlying cause is not clear rather than depression with a reason such as a relationship break up) and usually requires a course of up to 12 treatments. The memory loss etc is supposedly a tempory side effect!!??
The success rate that he had (working at the largest hospital for the mentally ill in Perth Australia) was around 80% - so yes it works for some and not for others.

I believe that in japan businessmen and corporate workers actually use it to re-boot when they are stressed - not that it's recommended for that!!
The history behind it goes back to the Greeks/Romans/Egyptions.
In Italy they once used insulin to produce the seziures to re-boot the brain.. but that was a long long long time ago and it's come very far since then.

Hope this hasn't been a total babble.. wanted to express what I had learnt in hopes it will help someone!