ARACHIDONIC-ACID TO EICOSAPENTAENOIC ACID RATIO IN BLOOD CORRELATES POSITIVELY WITH CLINICAL SYMPTOMS OF DEPRESSION

In this study of 20 moderately to severely depressed patients, diagnos ed using current research diagnostic criteria and excluding known bipo lar affective disorder and reactive depression, we investigated relati onships between severity of depression and levels and ratios of n-3 an d n-6 long-chain polyunsaturated fatty acids (PUFA) in plasma and eryt hrocyte phospholipids (PL). Severity of depression was measured using the 21-item Hamilton depression rating scale (HRS) and a second linear rating scale (LRS) of severity of depressive symptoms that omitted an xiety symptoms. There was a significant correlation between the ratio of erythrocyte PL arachidonic acid (AA) to eicosapentaenoic acid (EPA) and severity of depression as rated by the HRS (P < 0.05) and the LRS for depression (P < 0.01). There was also a significant negative corr elation between erythrocyte EPA and the LRS (P < 0.05). The AA/EPA rat io in plasma PL and the ratio of erythrocyte long-chain (C-20 and C-22 carbon) n-6 to long-chain n-3 PUFA were also significantly correlated with the LRS (P < 0.05). These findings do not appear to be simply ex plained by differences in dietary intake of EPA. We cannot determine w hether the high ratios of AA/EPA in both plasma and erythrocyte PL are the result of depression or whether tissue PUFA change predate the de pressive symptoms. We suggest, however, that our findings provide a ba sis for studying the effect of the nutritional supplementation of depr essed subjects, aimed at reducing the AA/EPA ratio in tissues and seve rity of depression.