Schizophrenia is a severe mental disorder defined by a complex combination of symptoms. The DSM-5 qualifies the “positive” symptoms of schizophrenia as hallucinations, delusions, and disorganized thinking and behavior. The “negative” symptoms involve social withdrawal and diminished emotional expression. The disease has an estimated heritability rate of around 80 percent (Khavari & Cairns, 2020). Environmental contributors such as maternal immune activation, obstetric complications, nutrient deprivation, childhood trauma, and various toxins have been identified (Khavari & Cairns, 2020). Therefore, the etiology of schizophrenia involves a heritable vulnerability and environmental exposure throughout prenatal, early life, and adolescent development.
Deep research of schizophrenia has been done in the last years by different scientists. For instance, the Khavari & Cairns article was published in 2020 in the international, peer-reviewed journal of molecular biology Cells. The authors review epigenomic dysregulation in schizophrenia based on postmortem analysis of brain and peripheral tissues in patients diagnosed with the disease. They examine the current literature discussing how changes in epigenomic markers such as DNA methylation, histone modification, and RNA mediation disrupt neural connectivity and lead to the development of the disease (Khavari & Cairns, 2020). This article is relevant to the etiology of schizophrenia because it is theorized that epigenetic marks mediate the response to environmental triggers in patients.
Khavari & Cairns (2020) discovered that the effect of changes in DNA methylation, histone modification, and RNA mediation might be more widespread than expected. First, exposure to environmental risk factors increases GAD1 promoter methylation and reduces mRNA expression, which are considered significant components of schizophrenia’s neuropathology (Khavari & Cairns, 2020). Second, reduced expression of one histone-modifying enzyme and increased expression of another in the prefrontal cortex have deteriorating effects on the brain. Third, several studies confirm that significantly disrupted miRNA and IncRNA expression adversely affects neural connectivity. While these changes may be the result of many years of the condition rather than its cause, the biological impact of these modifications is consistent with the current hypothesis regarding the etiology of schizophrenia. Disrupted epigenomic regulation in response to environmental triggers leads to decreased brain function and the onset of schizophrenia.
These findings are important to the etiology of schizophrenia because they identify the causes of the disease at a molecular level. The chromatin structure of the brain and disruptions in epigenomic regulation has a significant impact on “the etiological roots, the current state, and future course of illness” (Khavari & Cairns, 2020, p. 16). The study of epigenetic causes is particularly important to schizophrenia, considering its high heritability rate and environmental contribution. No single etiological root of the disease has been found yet. The most popular treatment option involves the chemical inhibition of dopamine receptors and is largely ineffective for relieving the “negative” symptoms of schizophrenia. These deficiencies suggest a role for epigenetics and neural development. Studies similar to Khavari & Cairns (2020) could potentially result in novel medical interventions, such as the invention of drugs that address epigenetic signaling or personalized treatment based on an individual’s epigenetic status.
In conclusion, schizophrenia is caused by a complex interplay of genetic and environmental factors. The Khavari & Cairns (2020), article focuses on the epigenomic factors that contribute to the development of the disease, such as disruptions in DNA methylation, histone modification, and RNA mediation. Their findings are based on a review of postmortem dissections of the brain and peripheral tissues in diagnosed patients. This information is important to the etiology of schizophrenia because it identifies how epigenetics contribute to disease phenotype, potentially resulting in more effective medical interventions.
Reference
Khavari, B., & Cairns, M. J. (2020). Epigenomic dysregulation in schizophrenia: In search of disease etiology and biomarkers. Cells, 9(8), 1-27.