Early maladaptive schemas and depression: Epigenetics as a possible link

Major depressive disorder (MDD) is a widespread mood disorder affecting millions of people. Because of heterogeneity and complexity of MDD, new hypotheses are needed to describe the pathological aspects of this debilitating disorder. Phenotypic changes by epigenetic modifications (DNA methylation, histone modifications, and the regulation of non-coding RNAs) cause long-lasting changes in gene expression leading to the development of MDD. On the other hand, Childhood maltreatment and trauma as early life adversities are associated with the development of dysfunctional early maladaptive schemas (EMSs) and MDD similarly produce long-term changes. Indeed, early life adverse patterns are closely related to EMS formation. The focus of this hypothesis will be on how epigenetics implicit EMSs. There are common characteristics between epigenetic modifications and EMSs: 1) both early life stress and epigenetic modulations have impact on expression of genes encoding proteins play key roles in MDD (e.g. brain derived neurotrophic factor, glucocorticoid receptor, serotonin transporter, and oxytocin receptor), 2) Both of them are induced synchronal by adverse social environment during childhood, 3) both of them are known to have a permanent, stable, and unchangeable effects on behavior, 4) both of them are linked to development of psychological disorders such as MDD. Overall, our hypothesis emphasizes that epigenetic factors are biological substrate of EMSs formation in psychological disorders, particularly MDD.