Psychiatric Genetics

Psychiatric Genetics is the study of the role of genetics in the development of mental disorders. Although many mental disorders are highly heritable, gene and environmental interactions play an important role.^[1]

• Psychotropics, including typical and atypical antipsychotics, selective serotonin reuptake inhibitors, and antiepileptics, interfere with important mitochondrial functions and may worsen symptoms.

• Cross-Disorder Group of the Psychiatric Genomics Consortium. Identification of risk loci with shared effects on five major psychiatric disorders: a genome-wide analysis. Lancet. 2013;381(9875):1371-1379.
• Duncan, L. E., Ostacher, M., & Ballon, J. (2019). How genome-wide association studies (GWAS) made traditional candidate gene studies obsolete. Neuropsychopharmacology, 44(9), 1518-1523.

• In the last 25 years, hundreds of studies have been published suggesting that a small set of genes or gene-variants increases an individual's risk for depression. These papers fuelled hopes that genetic testing might identify susceptibility to depression, and pharmaceutical companies could develop medications to target these specific groups.
• In 2019, a landmark study by Border et al. found that the 18 most highly-studied candidate genes for depression were actually no more associated with depression than genes chosen at random.^[2]
• The Serotonin Transporter Gene (5-HTTLPR) was among the most famous of the genes, and was popularly reported on in major studies and in the media in the last 25 years.
• It is important to understand that this does not mean that depression is not heritable (it is!).
  • But it does mean that depression is influenced by so many different gene variants that individually, each one has a tiny minuscule effect, underscoring the complex biopsychosocial phenomena of depression.^[3]

• Psychiatry at the Margins: A Note From Hyman on the Genetic Complexity of Psychiatric Disorders