The initial goal of precision psychiatry isn't complex machine learning or perfect biomarkers. It's about systematically collecting basic, meaningful data—like cognitive function—that we already know correlates with treatment outcomes. This simple act of consistent measurement provides a powerful foundation for better understanding patients.

The Hierarchical Taxonomy of Psychopathology (HITOP) model reveals that symptoms of mental health problems cluster into five major dimensions that closely correspond to the Big Five personality traits. This suggests mental illness can be understood as an extreme expression of normal personality variation.

Modern psychiatry defines disorders by a checklist of symptoms (e.g., via the DSM), treating the syndrome itself as the disease. This is unlike the rest of medicine, which views symptoms like a cough as signals of various underlying causes. This flawed approach has stalled progress by focusing on labels instead of mechanisms.

Moving beyond Freudian theory and the "chemical imbalance" hypothesis, "Psychiatry 3.0" views mental illness as a problem of brain circuitry. Treatments like TMS and psychedelics show that recalibrating these circuits can rapidly resolve symptoms, framing conditions like depression as correctable rather than a permanent deficit.

Decades-old symptom scales are often criticized but are irreplaceable because they possess "face validity"—they measure the symptoms patients actually experience. While they lack mechanistic insight, they capture the patient's subjective reality, which is the ultimate endpoint of any psychiatric treatment. No objective measure can replace asking "do they feel better?"

A diagnosis like autism may function like the 19th-century term 'dropsy' (swelling). It accurately describes a collection of symptoms but doesn't necessarily identify a single, unified underlying cause. The label captures a surface-level phenomenon, not a fundamental 'thing' in the world.

The initial hurdle for precision psychiatry isn't achieving 100% accuracy. The goal is to be meaningfully better than the current trial-and-error standard. Moving the needle on treatment remission from 30% to 40-45% would be a huge clinical success, creating a new benchmark and starting a virtuous cycle of improvement.

Instead of a categorical disease model (virus present/absent), mental health should adopt a dimensional approach like internal medicine. Just as blood pressure exists on a spectrum, psychological traits do too. Treatment decisions can be based on evidence-backed cutoffs for risk, eliminating the need for arbitrary diagnostic boxes.

The term "depression" is a misleading catch-all. Two people diagnosed with it can have completely opposite symptoms, such as oversleeping versus insomnia or overeating versus appetite loss. These are not points on a spectrum but discrete experiences, and lumping them together hinders effective, personalized treatment.