Please use this identifier to cite or link to this item: https://observatorio.fm.usp.br/handle/OPI/11787
Title: Bimodal Effect of Lithium Plasma Levels on Hippocampal Glutamate Concentrations in Bipolar II Depression: A Pilot Study
Authors: ZANETTI, Marcus V.OTADUY, Maria C.SOUSA, Rafael T. deGATTAZ, Wagner F.BUSATTO, Geraldo F.LEITE, Claudia C.MACHADO-VIEIRA, Rodrigo
Citation: INTERNATIONAL JOURNAL OF NEUROPSYCHOPHARMACOLOGY, v.18, n.6, 2015
Abstract: Background: The hippocampus has been highly implicated in the pathophysiology of bipolar disorder (BD). Nevertheless, no study has longitudinally evaluated hippocampal metabolite levels in bipolar depression under treatment with lithium. Methods: Nineteen medication-free BD patients (78.9% treatment-naive and 73.7% with BD type II) presenting an acute depressive episode and 17 healthy controls were studied. Patients were treated for 6 weeks with lithium in an open-label trial. N-acetyl aspartate (NAA), creatine, choline, myo-Inositol, and glutamate levels were assessed in the left hippocampus before (week 0) and after (week 6) lithium treatment using 3T proton magnetic resonance spectroscopy (1H-MRS). The metabolite concentrations were estimated using internal water as reference and voxel segmentation for partial volume correction. Results: At baseline, acutely depressed BD patients and healthy controls exhibited similar hippocampal metabolites concentrations, with no changes after 6 weeks of lithium monotherapy. A significant correlation between antidepressant efficacy and increases in NAA concentration over time was observed. Also, there was a significant positive correlation between the changes in glutamate concentrations over follow-up and plasma lithium levels at endpoint. Mixed effects model analysis revealed a bimodal effect of lithium plasma levels in hippocampal glutamate concentrations: levels of 0.2 to 0.49 mmol/L (n=9) were associated with a decrease in glutamate concentrations, whereas the subgroup of BD subjects with ""standard"" lithium levels (>= 0.50 mmol/L; n = 10) showed an overall increase in glutamate concentrations over time. Conclusions: These preliminary results suggest that lithium has a bimodal action in hippocampal glutamate concentration depending on the plasma levels.
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Instituto de Radiologia - HC/InRad

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LIM/44 - Laboratório de Ressonância Magnética em Neurorradiologia


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