Abstract Developing clinically useful brain-based biomarkers remains a central challenge in translational psychiatry and neurology. Traditional approaches focusing on disorder-specific signals have shown limited clinical utility. EEG, a scalable and non-invasive measure of brain function, illustrates the value of an alternative perspective: transdiagnostic and dimensional biomarker development. Here, we use low-frequency activity (LFA) as an illustrative example to demonstrate this framework. We