Altered hippocampal lipid profile in schizophrenia, bipolar disorder
MedWire News: The postmortem brains of patients with schizophrenia and bipolar disorder show an altered phospholipid profile, namely a decrease in omega-6 long-chain polyunsaturated fatty acids (PUFA), study results show.
However, levels of the omega-3 PUFA docosahexaenoic acid (DHA) were preserved, suggesting a "unique metabolic alteration associated with schizophrenia and bipolar disorder," say Hee-Yong Kim (National Institutes of Health, Bethesda, Maryland, USA) and colleagues in the Journal of Psychiatric Research.
A previous study of total fatty acid composition in the orbitofrontal cortex of patients with schizophrenia showed a 20% decrease in DHA relative to normal controls, and a reciprocal increase in omega-6 PUFAs.
While the prefrontal cortex has been intensively studied in the pathophysiology of schizophrenia and bipolar disorder, less attention has been given to the role of the hippocampus.
In the current study, the researchers assessed phospholipid composition in postmortem hippocampus samples from 35 individuals with schizophrenia, 34 individuals with bipolar disorder, and 35 mentally healthy controls using liquid chromatography/electrospray ionization-mass spectrometry.
They found no significant differences among the samples in levels of omega-3 PUFAs or any of the phospolipid species phosphatidylserine (PS), phosphatidylethanolamine (PE), or phosphatidylcholine (PC).
Kim and colleagues note that this contradicts previous findings in the cortex, suggesting that DHA loss "may not be a general phenomenon, but specific to certain regions of the diseased brain."
However, there was a 10.6% decrease in the omega-6 PUFA, docosapentaenoic acid (DPA) in schizophrenia samples and a 7.5% decrease in bipolar disorder samples relative to those from controls. Meanwhile, another omega-6 PUFA arachidonic acid was decreased by 5.3% in schizophrenia and 2.9% in bipolar disorder samples relative to controls.
Furthermore, looking within the phospholipid classes there were several omega-6 PUFA subspecies that were reduced in schizophrenia and bipolar disorder samples, for example among the PC fraction 16:0,20:4, 16:0,22:5, and 18:0,22:5 were all reduced relative to controls.
"Our findings on the loss of DPA, particularly in specific phospholipid classes, suggest an involvement of this fatty acid and related metabolism in the neuropathology of schizophrenia or bipolar disorder, although the mechanism for this decreased is unclear," Kim and colleagues conclude.
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By Andrew Czyzewski