It's crazy, isn't it? Cutting gluten has become somewhat of a meme, but a meme repeated enough times must have some kind of truth to it.
I've self diagnosed myself to a combination of depression/cyclothymia/bipolar disorder. Basically, I've been working at 50% potential, on a good day, for the past 10 years.
Interested in the science behind ketogenic diets, I've tried to cut all grains and processed food for many month-long stretches, and I've always noticed my brain being sharper, and moving farther and farther away from the "black dog". But eventually I get back in the trap and it's extremely hard to pull myself up again — impossibly hard cutting grains with Italian friends and family.
Keto probably isn't the solution, but I'm more and more convinced the key lies in our gut, not in our brain chemistry.
EDIT: depression is a common modern "disease", and in my ignorant opinion, I'm convinced there's two types of depression:
You might be depressed if your life is in the shitter, and there's no sane way of getting out of it. Think bad marriage or crippling loneliness.
You might also be depressed because your chemistry isn't optimal, because of what you eat or bad health.
I believe most modern depression is of the latter type, and in both cases medication treats the symptoms, not the actual cause. We need to do more work on this.
Again, this is my personal opinion, and I might be talking out of my arse.