Decreased brain intracellular pH measured by P-31-MRS in bipolar disorder:a confirmation in drug-free patients and correlation with white matter hyperintensity

The authors have previously reported decreased intracellular pH (pHi) in th e frontal lobes in euthymic bipolar patients treated with lithium using P-3 1- MRS. White matter hyperintensity (WMHI) is frequently seen in bipolar di sorder. To examine a possible effect of lithium on pHi and the relationship between pHi and WMHI, seven drug-free euthymic bipolar patients were exami ned, and T-2-weighted MRI were examined in 14 previously reported bipolar p atients. Drug-free patients showed significantly lower pHi than controls. W MHI was associated with low pHi and increased phosphodiester peak. These re sults suggest that decrease of pHi is not an effect of lithium but is inste ad related to the pathophysiology of illness. Decrease of pHi and increase of the PDE peak may be the biochemical basis of WMHI in bipolar disorder.