The real way to change your brain for the better (or at least slow its decline) is to sleep (5) and eat right (3) at regular intervals (7), avoid inactivity (1) (6), get regular sunlight (2) and exercise (4), be moderately (eu)stressed (challenge yourself mentally (9) and physically), avoid chronic excessive stress (10), fast (or just skip meals) occasionally (8) and have a rich social life (1).

Sources:

(1) https://www.researchgate.net/profile/Karin_Volkers/publicati... and http://www.nature.com/nrn/journal/v13/n3/full/nrn3151.html

(2) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3448747/

(3) http://onlinelibrary.wiley.com/doi/10.1002/ana.23944/pdf

(4) http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2796.2010....

(5) http://journals.lww.com/co-psychiatry/Abstract/2014/11000/Im...

(6) http://europepmc.org/articles/pmc3915771

(7) https://www.researchgate.net/profile/Kelly_Baron2/publicatio... and http://www.pnas.org/content/111/47/16647.long

(8) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3206295/

(9) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4227476/ and http://mggu-sh.ru/ipgit/Kupriyanov_Eustres.pdf

(10) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3410434/

(edit to match points to sources)