No abstract

Objective: There are several models of staging in bipolar disorder (BD), but none has been validated. The aims of this study were to empirically investigate clinical variables that may be useful to classify patients in clusters according to stage and study the association with biomarkers as biological validators. Method: This was a historical cohort study. Patients (n = 115) diagnosed with BD and not in an acute episode and first-degree relatives of patients diagnosed with BD (n = 25) were recruited. Sociodemographic, clinical, and functional data were collected. Serum cytokines, brain-derived neurotrophic factor, and biomarkers of lipid and protein oxidation were assessed. Cluster analysis was carried out to build a model of staging, and logistic regression was conducted to study associations between the model and biomarkers. Results: Cluster analysis divided the sample into two equitable groups, denominated early and late stage, with empirical cutoffs for the Functioning Assessment Short Test score, number of episodes, age at onset of the disorder, and time elapsed since first episode. In the logistic regression, IL-6 was associated with late stage (P = 0.029). Conclusion: This study supports that clinical, functional, and biochemical variables may help to define a classification of staging in BD. Significant outcomes• A model of staging based on early and late stages according to functioning, number of episodes, age at onset of the disorder, and time elapsed since the first episode can be feasible and useful in bipolar disorder.• IL-6 is a valid biological biomarker for this proposal of staging in bipolar disorder. Limitations• Patients with subsyndromal symptoms were not excluded from the sample. • Biomarker assessment was carried out peripherally. • Lack of a prospective assessment hampers to test the validity of a model of staging.

Bipolar disorder (BD) is a severe chronic psychiatric disorder that has been associated with cellular dysfunctions related to mitochondria, neurotrophin levels, and oxidative stress. Evidence has shown that endoplasmic reticulum (ER) stress may be a common pathway of the cellular changes described in BD. In the present study we assessed unfolded protein response (UPR) and the effects of this cellular process on lymphocytes from patients with BD. We also evaluated whether the stage of chronicity of BD was associated with changes in UPR parameters. Cultured lymphocytes from 30 patients with BD and 32 age- and sex-matched controls were treated with tunicamycin, an ER stressor, for 12 or 24 h to measure levels of UPR-related proteins (GRP78, eIF2α-P, and CHOP) using flow cytometry, and for 48 h to analyse ER stress-induced cell death. In healthy controls but not in patients we found an increase in levels of GRP78, eIF2α-P, and CHOP after ER stress induction. In addition, tunicamycin-induced cell death was significantly higher in patients compared to controls. More importantly, early-stage patients did not differ from controls while the late-stage patients showed an impaired ER stress response. Thus, dysfunction in ER-related stress response may be associated with decreased cellular resilience in BD and illness progression.