By integrating genome-wide data from a million-plus people with 14 psychiatric disorders, a 2026 Nature study marks a turning point in psychiatric science, showing many common psychiatric diagnoses are not genetically separate diseases. Instead, they share genetic liability (five genomic factors) across major psychiatric diagnoses, shaped by neurodevelopmental biology and life experiences. These findings challenge the disease model in psychiatric diagnoses and the Diagnostic and Statistical Manual of Mental Disorders (DSM).

Psychiatric manual categories still help with communication and treatment planning, but are imperfect proxies for personalized medicine or treatment predictions. The study confirmed what some clinicians already knew: How patients respond to treatment matters more than the disorder’s name. Also, comorbidity is common, and patients often move between diagnoses in the same cluster.

Depression, anxiety, and posttraumatic stress disorder (PTSD) often present together because of overlapping tendencies like negative emotions and stress sensitivity. However, when a patient has both major depressive disorder and generalized anxiety disorder, DSM psychiatry considers them two separate illnesses. The new genetic data suggest that these disorders cluster together due to shared neurodevelopmental risks. Cross-disorder psychiatric genomics shows high comorbidity and genetic overlap. Patients often move within diagnostic clusters over time, such as anxiety preceding depression, and psychotic symptoms preceding a bipolar diagnosis. These are not random transitions but expressions of a latent liability interacting with environment, maturation, trauma, and life experiences. Genomic phenotypes may help psychiatry move away from the trend of stacking one diagnosis on another in a single person.

Cross-disorder genomics strongly reinforces substance addiction as a single disease category: Alcohol, cannabis, opioid, and nicotine use disorders cluster together genetically. Substance use disorder (SUD) diagnoses support a shared addiction-liability dimension across major substances. Reflecting differences in reward sensitivity, impulsivity, stress reactivity, and executive control, some individuals are more susceptible to developing SUDs, regardless of which drug they encounter first.

Highly stereotyped behavioral patterns present with these addictions, and compulsive use, escalation, relapse, drug-seeking, and use despite harm are all hallmarks of addictive conditions, regardless of the drugs involved. Drug testing and laboratory data are commonly utilized to confirm a diagnosis. With alcohol use disorder (AUD), for........

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