Others could better comment on the DNA field, but I would definitely look at the discussion of several of the brain fields : Blood Brain Barrier, GPDL 1, ISIRB and RMB3., brain regeneration, experimental alzheimer’s treatment . This is by no means an exclusive list. I’m sure others will chime in with great suggestions.
I would also look at the Induced Mots - c Production , even though it’s not brain field per se, it mimics exercise, which is quite neuroprotective.
There are lots fields that you can purchase that would be applicable, though I think you can do well with the fields suggested above and ones that others suggest or that your own research reveals. If you are considering a purchased field, please read the comments relating to the smart cells field which comes bundled with the plasma brain of youth, If there’s a better value in this world than that combination, I don’t know of it.
For depression, I would look at this search, but I don’t trust my instincts beyond that. Again, others will have better suggestions.
Good Luck