Objectives: Electroconvulsive therapy (ECT) is commonly indicated for refractory psychiatric disorders. However, little research has compared response across diagnoses. Here, we aimed to evaluate the relative impact of diagnosis and clinical staging as response predictors in a cross-diagnostic sample. Methods: In a retrospective cohort of adult inpatients (n=287) who underwent at least six sessions of ECT, we investigated predictors of complete response (a clinical global impression of 1) to ECT. We use adjusted regression models to estimate the impact of clinical diagnosis and staging on complete response and dominance analysis to assess the relative importance of these predictors. Results: Those for whom a depressive episode was a primary indication for treatment were the most likely to have complete improvement, while those with psychosis were the least likely; clinical stage had a significant influence on outcome in all diagnoses. A diagnosis of psychosis was the strongest predictor of non-response. Conclusions: A diagnosis of psychosis (mainly schizophrenia) was the strongest predictor of non-response. We also found that clinical staging can aggregate information on ECT response that is independent of clinical diagnosis.

INTRODUCTION: The use of clinical staging models is emerging as a novel and useful paradigm for diagnosing severe mental disorders. The term "neuroprogression" has been used to define the pathological reorganization of the central nervous system along the course of severe mental disorders. In bipolar disorder (BD), neural substrate reactivity is changed by repeated mood episodes, promoting a brain rewiring that leads to an increased vulnerability to life stress. METHOD: A search in the PubMed database was performed with the following terms: "staging", "neuroprogression", "serum", "plasma", "blood", "neuroimaging", "PET scan", "fMRI", "neurotrophins", "inflammatory markers" and "oxidative stress markers", which were individually crossed with "cognition", "functionality", "response to treatments" and "bipolar disorder". The inclusion criteria comprised original papers in the English language. Abstracts from scientific meetings were not included. RESULTS: We divided the results according to the available evidence of serum biomarkers as potential mediators of neuroprogression, with brain imaging, cognition, functioning and response to treatments considered as consequences. CONCLUSION: The challenge in BD treatment is translating the knowledge of neuronal plasticity and neurobiology into clinical practice. Neuroprogression and staging can have important clinical implications, given that early and late stages of the disorder appear to present different biological features and therefore may require different treatment strategies.