Why does shock treatment cause seizures and whhat r the side effects this is for depression?

Memory loss: I have treated severely depressed/suicidal patients who agreed to shock treatments after failing numerous meds. (by qualified md) by far their greatest complaint has been memory loss. The loss generally relates to a brief period of time around the treatment, but in cases of a longer series of treatments, the memory loss was more extensive. However, in my opinion, the treatments saved lives.

Electroconvulsive Rx: Electroconvulsive treatment (ECT) uses a small electric current to produce a generalized cerebral seizure under general anesthesia. It's usually used for very severe depression and occasionally for certain other conditions. The mechanism of action is unknown, but it may increase monoamine neurotransmitters. It's a relatively safe procedure. There can be some amnesia which recovers variably.