This review paper summarizes recent research showing how epigenetics change the brain as we get older.
References:
Hwang, J., Aromolaran, K. A., & Zukin, R. S. (2017). The emerging field of epigenetics in neurodegeneration and neuroprotection. Nature Reviews Neuroscience, 18(6), 347-361. doi:10.1038/nrn.2017.46