Epigenetic Alterations and Neuropsychiatric Disorders: A Review

Many neurological and psychiatric disorders are not due to mutations in a specific gene; rather, they are attributed to dysregulation of genes’ functions and signals that control their expression. Complex 'epigenetic' mechanisms regulate various gene activities with long-lasting effects within mature neurons and other cells of brain tissue. The present study reviewed related investigations up to 2021 by searching keywords including epigenetics, DNA methylation, microRNA, RNA editing as well as psychiatric disorders, schizophrenia, autism and bipolar disorder in PubMed database. Among collected articles, the most relevant research articles related to the topic of this article were selected and reviewed. Currently, at least four epigenetic mechanisms are known, that through altering DNA, RNA or histone codes, regulate genes’ expression levels. Meanwhile, these epigenetic mechanisms themselves are under the influence of internal and environmental factors and may be dysfunctional secondary to malnutrition, contaminants, toxins, drugs, substances, infections, etc. Many studies have shown that various epigenetic aberrations are involved in the expression of genes involved in psychiatric disorders, such as schizophrenia, autism, and bipolar disorder. A comprehensive investigation on epigenetic alterations and the environmental factors that mediate these alterations can help to improve preventive and therapeutic strategies in neuropsychiatric diseases.