Omega-3/omega-6 fatty acid ratios in different phospholipid classes and depressive symptoms in coronary artery disease patients

• Omega-3/6 ratio in major phospholipid classes was not associated with depression.
• Phosphatidylinositol and sphingomyelin classes may be associated with depression.

Depressive symptoms are highly incident among coronary artery disease (CAD) patients and increase mortality. Reduced ratios of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (omega-3 fatty acids) to arachidonic acid (AA, omega-6 fatty acid) concentrations have been linked with depressive symptoms in CAD. It remains unclear whether depressive symptoms are differentially associated with that ratio in different phospholipid classes, and this may have mechanistic implications. This study investigated associations between depressive symptoms in CAD patients and the EPA + DHA to AA ratio in the major phospholipid classes. This was a cross-sectional study of stable CAD patients. Sociodemographic, medical, medication, and cardiopulmonary fitness data were collected from each patient. Each patient was assessed for depressive symptoms using the 17-item Hamilton Depression Rating Scale (HAM-D). The percentage of EPA, DHA, and AA in each erythrocyte phospholipid class was determined using gas chromatography from fasting blood. Relationships between EPA + DHA to AA ratios and depressive symptoms were assessed using linear regression and were corrected for multiple comparisons. Seventy-six CAD patients were included (age = 61.9 ± 8.5, 74% male, HAM-D = 7.2 ± 5.9). In a backward elimination linear regression model, lower EPA + DHA to AA in erythrocyte phosphatidylinositol (B = −12.71, β = −0.33, p < .01) and sphingomyelin (B = −2.52, β = −0.37, p < .01) was associated with greater depressive symptom severity, independently of other known predictors. Other phospholipid classes were not associated with depressive symptoms. In conclusion, the relationship between EPA + DHA to AA ratios and depressive symptoms in CAD may not be consistent across phospholipid classes. Continued investigation of these potentially differential relationships may clarify underlying disease mechanisms.