The hippocampus gets fried from trauma/stress. Cells are damaged and lost. There are studies out there saying that antidepressants help the hippocampus grow new cells in people with PTSD and other emotional traumas.
I've been trying the Walsh advice: phosphatidyl serine and MSM (as a methyl donor) during the day and melatonin at night. Seems to be working. I sure sleep a lot deeper and wake up feeling rested.
Not that I was that bad off when I started the above, but worth a shot...it's cheaper than Lam. I like Lam and all but I think his protocol might be a little dated.