Abnormal ratios of omega-6 to omega-3 fatty acids were associated with the presence of bipolar disorder and the severity and duration of major depressive disorder, according to the results of a recent study published in the Journal of Affective Disorders.
In this cross-sectional analysis, researchers recruited patients with euthymic bipolar disorder (n=31), depressive bipolar disorder (n=22), and major depressive disorder (n=34), and people without psychiatric disease (n=31). Serum samples were evaluated for relative and absolute quantities of saturated fatty acids, polyunsaturated fatty acids, and monounsaturated fatty acids.
Total levels of polyunsaturated fatty acids, saturated fatty acids, and monounsaturated fatty acids were not significantly different among groups.
Total omega-6 to omega-3 ratios were not significantly different among groups, but patients with depressive bipolar disorder had higher arachidonic acid to eicosapentaenoic acid ratios relative to patients with euthymic bipolar disorder (P =.01), major depressive disorder (P =.006), and controls (P =.019). Similarly, arachidonic acid to eicosapentaenoic acid plus docosahexaenoic acid ratios were significantly higher in patients with depressive bipolar disorder compared with patients with euthymic bipolar disorder (P =.002) and controls (P =.015).
The ratio of arachidonic acid to eicosapentaenoic acid (P =.002) and ratio of arachidonic acid to eicosapentaenoic acid plus docosahexaenoic acid (P =.012) were positively correlated with illness duration in patients with major depressive disorder but not in those with either category of bipolar disorder.
The study investigators concluded that the results “add to a growing body of evidence related to lipid metabolism imbalance in the pathophysiology [of bipolar disease and depression] and suggest a potential subset of stage-related lipid biomarkers in [bipolar disorder] depression.”
Scola G, Versace A, Metherel AH, et al. Alterations in peripheral fatty acid composition in bipolar and unipolar depression [published online January 6, 2018]. J Affect Disord. doi:10.1016/j.jad.2017.12.025