Biology and Genetics in DSM-5

DSM-5 includes a number of statements concerning the biology and genetics of mental disorders, and these represent a significant landmark in the history of psychiatry. According to DSM-5, there are no laboratory tests, x-rays, or other biological markers for any mental disorder; there is no physiological specificity to any mental disorder; there is no genetic specificity to any mental disorder; and there is no symptom specificity to DSM-5 disorders. DSM-5 disorders, according to the manual, have porous boundaries with each other, have high rates of comorbidity, and fluctuate a great deal over time. The risk genes for mental disorders number in the hundreds, each contributes perhaps 1%–2% to the overall risk, and the same genes confer risk for multiple DSM-5 categories of disorder. The idea that DSM disorders are separate diseases with distinct pathophysiologies has been disconfirmed by the DSM-5, and therefore by the American Psychiatric Association, as it has by the National Institutes of Mental Health.