Like
@itsKismet said - I think there are times, extreme times, when it is appropriate. My definition of extreme involves unremitting psychosis, to a degree that the options are lifetime inpatient with constant suffering. If you're a functional schizophrenic who occasionally loses it, but generally you are happy and living in assisted care - well, that's not constant suffering. If you cannot make things shift with medication and you are non-functional, meaning you cannot communicate, you are either frozen or in constant fear - your mind is trapping you, basically - then yes, it's the best we have.
I've met people who have had it (or regularly need it) who are willing to trade the memory loss for a life they can live in the present that is relatively pain-free. And I've met people who have had it who regret it with every inch of themselves. What bothers me the most, probably, is that there is no real data supporting what seems to be the
fact of memory loss. You talk to people - consistently, they will tell you about memory loss. You talk to doctors, they will tell you that the occurrences of memory loss are 'marginal'. The good doctors will then say, "but memory loss appears in practice to be inevitable". And the others just shrug and say, "the data says memory loss is a rare occurrence".
It has gotten more calibrated than it was in the 1960's, but really, there is still a ton of guesswork going into it. A bit like how being a good anesthesiologist is a combination of training and experience, being able to administer ECT well - for maximum positive and minimal negative impact - is a skill that is worth seeking out, if you are going to go that route. (I say a bit like because the science in putting people to sleep for surgery is still way more precise than the science in sending volts through the brain).
I did a ton of research into it, as I was slipping into a very unremitting, dysfunctional depression - and really, really considered it. But ultimately, I'm not willing to risk my recall. I use recall professionally. I don't know how I'd be who I am without recall. I don't care about the long-term loss as much, but the short-term would really do me in. And it is also not recommended if you don't have a care system or support system in place, which I don't.
Using it on anyone under the age of 25 is, in my opinion, criminal - unless that patient is persistently 'locked' in a psychotic or catatonic state - and even then, using it on someone under 18/19 is just premature. The brain is still changing. I only give 18-25 some leeway because it's hard to have absolute rules with things like this. But 25 is the generally agreed-upon age (in the medical community) of full maturation of the brain - so that seems like a safe number to me.
And I think doctors should apply a great deal of discretion and caution in selecting who they will consent to give the treatment to. Of course it's best if the patient can consent, but when they can't, it really should be a court of last resort.