Carole E. Siegel

Abstract Neuroimaging-based subtyping is increasingly used to explain heterogeneity in psychiatric disorders. However, the clinical utility of these subtyping efforts remains unclear, and replication has been challenging. Here we examined how the choice of neuroimaging measures influences the derivation of neuro-subtypes and the consequences for clinical delineation.

1 INTRODUCTION Clustering methods are used to search for the structure of a population based on sample data by partitioning units into groups based on their dissimilarities. Measures to characterize similarities or resemblances in an unsupervised setting between pairs of units are many and varied and are critically important in the search for structure in data.

Abstract Post-traumatic stress disorder (PTSD) is a mental disorder diagnosed by clinical interviews, self-report measures and neuropsychological testing. Traumatic brain injury (TBI) can have neuropsychiatric symptoms similar to PTSD. Diagnosing PTSD and TBI is challenging and more so for providers lacking specialized training facing time pressures in primary care and other general medical settings.