Background. No study to date has examined the effects of mood stabilizer alone and the combination of mood stabilizer and atypical antipsychotic, quetiapine, on hippocampal neurochemical markers of bipolar disordered patients concurrently. We therefore undertook a proton magnetic resonance spectroscopy (1H MRS) study of drug-free patients with bipolar disorder (drug-free group), patients undergoing valproate treatment (valproate group), patients administered valproate+quetiapine (valprote+quetiapine group) and healthy controls, focusing on the in vivo neuroanatomy of the hippocampus.

Method. Thirty patients from the Firat University School of Medicine Department of Psychiatry and 10 healthy controls gave written informed consent to participate in the study. The patients and controls underwent proton magnetic resonance spectroscopic imaging (1H MRSI), and measures of N-acetylaspartate (NAA), choline-containing compounds (CHO), and creatine+phosphocreatine (CRE) in hippocampal regions were obtained.

Results. The drug-free patients had significantly lower NAA/CRE and NAA/CHO ratios compared with the valproate and valproate+quetiapine groups and the healthy controls. The lower NAA/CRE and NAA/CHO ratios remained statistically significant even after covarying for age or whole brain volume compared with the valproate and valproate+quetiapine groups and healthy controls. In post hoc comparisons, a significant difference was found between the valproate+quetiapine group and the valproate group only with regard to NAA/CHO.

Conclusion. Our findings suggest that valproate has a neuroprotective effect. In post hoc comparisons, a significant difference was found between the valproate+quetiapine and the valproate group with regard to NAA/CHO, indicating that the addition of quetiapine further increases the level of NAA and provides an additional neuroprotective effect.