The American Psychiatric Association is preparing to modernise the DSM, the standard diagnostic manual for mental illness, by incorporating biology for the first time since its creation. The current edition, DSM-5, published in 2013, has been criticised for relying solely on clinical judgement of symptoms without objective biological measures, which critics argue risks medicalising ordinary suffering and undermines the reliability of psychiatric diagnoses. This shift matters because it could reshape how conditions are diagnosed and researched worldwide, given the DSM's central role for clinicians and scientists alike.

The article's author, a member of the DSM's strategic committee from May 2024 to August 2026, explains that reliable biomarkers, objective measures such as blood tests or scans used routinely in other areas of medicine, barely exist for mental illness, with the notable exception of certain proteins linked to Alzheimer's disease. This is because the biological changes underlying conditions such as depression, anxiety, schizophrenia and bipolar disorder are subtle, poorly understood, and entangled with strong environmental factors like family history and trauma. Psychiatric disorders are also increasingly understood as overlapping behavioural syndromes rather than discrete illnesses, with conditions such as major depressive disorder and schizophrenia likely comprising several biologically distinct subgroups, making a single unifying biomarker for any one diagnosis unlikely.