When to resort to ECT is a subjective decision of doctor and patient. It is clear it should come after other treatments failed. But there is no clear line.
Spectrums extend continuously from normal to disorders. So if you believe depression is a spectrum you must also believe that no treatment is necessary for some people with depression. However if depression is a disorder there may be some cases that are on the margins that aren’t quite depression that still warrant some forms of treatment.
DSM V has depression as depressive disorders, but lists “Schizophrenia Spectrum” and “Autism Spectrum” so I invite you to consider what distinction for spectrum is being used.
