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™]) 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™.
RESULTS: BD I patients were relatively hyperpolarized, with an MPR™ of .601 (± standard deviation .0179), compared with non-bipolar patients (MPR™ .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™.