I think those people were not depressed (which I think it's a very compelx issue), they were just extremely deficient in magnesium. If magnesium would be such an effective cure for depression, it would be well known and used, and it is not. I'm not saying magnesium doesn't help with depression, I think it does indeed. But Eby's claims are way exaggerated. IIRC the n of the study was 8. The authors are just Eby and his wife. And the "n" were people close to them IIRC. No double-blinded. No placebo controlled. And they are not MD's, ND's, or have any scientific credentials to design experiments with a minimum degree of reliability. And besides that, my anecdotal experience and that of a few people I know that tried magnesium is that it helps to alleviate anxiety and stuff but doesn't cure depression. I don't even know how this "paper" made its way to pubmed.
I'm sure you agree haidut that "depression" is a vague term including lots of sociocultural/biochemical issues. How in hell is it possible that people get cured or symptomatically relieved from a single illness depresion with such different cures like all sorts of psychotherapy, changin a life situation, thyroid, aminoacids including tryptophan, bowel and liver cleanses, chinese medicine, removing amalgams, b12 shots, exorcisms, you name it. It must be different illnesses disguised as depression.
You could say the same about almost any supplement, including glycine, thyroid, and sadly even food... If it were a cure, none of us would have any metabolic problem and it would all be ancient history by now. But I am open to the idea that magnesium could be just as a powerful bandaid as other good supplements or hormones, yet cheap and simple. I find it to be calming in the same sort of way as light, cyproheptadine, progesterone,...