LAUSR

Traditional attempts to characterize the brain pathophysiology associated with mental illnesses have relied on relating symptoms to a static snapshot of abnormal brain structure or function. Over the last few decades, however, it has become increasingly clear that many or most psychiatric disorders are the consequence of atypical brain development.1 As such, the pathophysiology of mental illnesses may be better understood by characterizing the dynamic changes in brain structure or function that unfold over time and ultimately result in psychiatric symptoms. One important concept that has emerged out of studies that have examined longitudinal trajectories resulting in mental illnesses is the concept of equifinality-that multiple different trajectories can result in the same symptoms in adolescence or adulthood.2 If proved to be true, equifinality is a fundamentally important principle because it suggests that even if two patients have the same symptoms, the cascade of brain changes that ultimately resulted in these symptoms differed. Potentially diverse monitoring and treatment strategies would be required to detect and treat patients with the same set of symptoms. There would be no "one-size fits all" approach to screening and treating patients, and clinicians would ultimately have to learn to identify and alter multiple different risk trajectories.