[Building precision psychiatry: why and how?].

Precision psychiatry aims to identify homogeneous subgroups of patients using biomarkers, which could revolutionize current diagnostic frameworks and raise hopes for personalized treatments. Early examples in neuropsychiatry demonstrate the feasibility of this approach, such as the reclassification of dementias in neurology based on biomarkers such as amyloid plaques and tau proteins, and significant advances in neurodevelopmental disorders such as autism, where genetic heterogeneity has reshaped diagnostic perspectives. To achieve this vision, major challenges must be overcome, including the establishment of large transdiagnostic cohorts, the integration of multimodal data such as imaging, genomics, or digital phenotyping, and the application of advanced statistical methods such as clustering, normative modeling and digital twins. While this strategy promises more precise and effective care tailored to individual needs, it also challenges traditional classifications and forces the psychiatric community to rethink its foundational paradigms in light of biological knowledge.