Increased thalamic phospholipid concentration evident in bipolar I disorder

Background: Bipolar disorder is characterised by changes in brain metabolites, as measured by ¹H-MRS. However, there is no consistent metabolic profile for bipolar disorder, which includes changes in N-acetyl-aspartate (NAA), choline metabolites and myo-inositol. The aim of the present paper is to add to this literature of ¹H-MRS, the metabolite profiles in bipolar disorder. Methodology: Nineteen individuals with euthymic bipolar I disorder and eight control participants were recruited for the present study. ¹H-MRS chemical shift imaging (CSI) was used to measure NAA, choline metabolites and myo-inositol of several bilateral brain areas potentially involved in bipolar disorder: hippocampal complexes, brain stem including the locus coeruleus, and thalami. Results: Compared with healthy controls, individuals with bipolar I disorder showed increased choline metabolites in bilateral thalami and increased NAA in left hippocampus. The ¹H-MRS data were not influenced by age, symptom severity, or medication status. Conclusions: Our present findings suggest that individuals with bipolar I disorder have increased phospholipid concentration in the thalami and increased NAA concentration in the left hippocampus. While MRS data on bipolar data remain somewhat inconsistent, the findings here are consistent with other evidence supporting the hypothesis that dysfunctional thalamocortical gating plays a role in bipolar disorder.