Brain lipid concentrations in bipolar disorder

Reduced concentrations of docosahexaenoic acid (DHA, 22:6n − 3) and arachidonic acid (AA, 20:4n − 6) have been reported in the postmortem bipolar disorder (BD) brain. Additionally, an increased prevalence of BD has been related to low dietary intake of fish, and dietary supplements containing fish products or DHA have been reported to ameliorate BD symptoms. These observations suggest that brain lipid metabolism, particularly involving DHA, is disturbed in BD. To test this suggestion, concentrations of different lipids were measured using internal standards in postmortem frontal cortex from eight BD patients and six matched controls. Compared with control cortex, the BD cortex showed no statistically significant difference in mean concentrations (per gram wet weight) of “stable” lipids (total lipid, total phospholipid, individual phospholipids, or cholesterol), of unesterified fatty acids, or of esterified DHA or AA within stable lipids. Fractional esterified AA and DHA concentrations also did not differ significantly between groups. Some fatty acid concentration differences were found in low-abundant cholesteryl ester. These results do not support the hypothesis of disturbed brain lipid concentrations, including concentrations of AA and DHA, in BD. Positron emission tomography might be used, however, to see if brain AA or DHA kinetics are disturbed in the disease.