Epigenetic Mechanisms in Psychiatric Disorders – Major Depression, Psychosis and Addiction

Posted on:March 3, 2021
Last Updated: April 12, 2024
Time to read: 11–13 minutes

Epigenetics is the study of heritable changes that alter gene expression levels without altering the DNA sequence.[Deans & Maggert, 2015] 

However, there are a multitude of poorly defined definitions that confer and contrast how epigenetics is defined. In its broadest sense, epigenetics can be considered as “heritable memory”, an adaptive and dynamic process that ensures proper genomic function through the regulation of gene expression activity.[Jaenisch & Bird, 2003], [Gibney & Nolan, 2010]

According to the NIH Epigenomics Roadmap Project:

Epigenetics refers to both heritable changes in gene activity and expression (in the progeny of cells or of individuals) and also stable, long-term alterations in the transcriptional potential of a cell that are not necessarily heritable. 

Experiences during an individual’s life modify genetic expression directly and indirectly. [Lacal et al., 2018]


  • How the organism responds to a changeable environment (i.e., more ontogenetic flexibility)

2. Indirect:

  • How the offspring will increase their likelihood of surviving in a specific environment—that is, how information is transmitted to offspring regarding the environment that they will encounter (i.e., phylogenetic flexibility)