Staging bipolar disorder: clinical, biochemical, and functional correlates.

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.

Val66Met polymorphism and serum brain-derived neurotrophic factor in bipolar disorder: an open-label trial.

OBJECTIVE: Brain-derived neurotrophic factor (BDNF) is consistently associated with acute mood episodes in bipolar disorder, but there is a lack of longitudinal data to support this hypothesis. In this 16-week open-label clinical trial, we tested the predictive role of BDNF Val66Met polymorphism on serum BDNF levels and the relationship of serum BDNF and clinical response in people with bipolar disorder during an acute illness episode. METHOD: Sixty-four people with bipolar disorder who were medication-free at baseline and in an acute mood episode were recruited. They were matched with 64 healthy controls. Clinical evaluation, serum BDNF, and BDNF Val66Met polymorphism were determined at baseline, and change in serum BDNF was assessed in patients at weeks 2, 4, 8 and 16. RESULTS: There were no differences between patients and controls in serum BDNF or in frequencies of the BDNF Val66Met polymorphism genotype at baseline. The multivariable model showed that Met carriers had a significantly different change in BDNF levels compared with Val homozygotes. Not achieving a complete remission was also associated with lower prospectively assessed BDNF levels. CONCLUSION: This study provides the first longitudinal evidence that both the BDNF Val66Met polymorphism and remission status predict change in circulating BDNF levels.