Validation of a diagnostic screening blood test for bipolar disorder

BACKGROUND: Bipolar disorder is difficult to diagnose, and probably is both overdiagnosed and underdiagnosed. Misdiagnosis has deleterious consequences for the prognosis of the disorder. In a previous study (n = 134), measurement of blood cellular membrane potential (expressed as membrane potential ratio [MPR (TM)]) diagnosed bipolar illness with a sensitivity of .78 and a specificity of .88. The current study was performed as a validation of the initial study. METHODS: We recruited consecutive outpatients with DSM-IV-diagnosed bipolar I disorder (BD I) and those without bipolar illness (n = 153) and measured their MPR (TM). RESULTS: BD I patients were relatively hyperpolarized, with an MPR (TM) of .601 (+/- standard deviation .0179), compared with non-bipolar patients (MPR (TM) .675 +/- .0174). The sensitivity and specificity for BD I are .93 and .90, respectively. CONCLUSIONS: Before clinical application, future studies must utilize consensus diagnosis as the "gold standard" diagnosis and examine the effect of mood-stabilizing drugs on MPR (TM).