Lowered ω3 polyunsaturated fatty acids in serum phospholipids and cholesteryl esters of depressed patients

Depression is associated with a lowered degree of esterification of serum cholesterol, an increased C20:4 omega 6/C20:5 omega 3 ratio and decreases in omega 3 fractions in fatty acids (FAs) or in the red blood cell membrane. The aims of the present study were to examine: (i) serum phospholipid and cholesteryl ester compositions of individual saturated fatty acids (SFAs), monounsaturated FAs (MUFAs) and polyunsaturated FAs (PUFAs) in major depressed patients vs. healthy volunteers; (ii) the relationships between the above FAs and lowered serum zinc (Zn), a marker of the inflammatory response in depression; and (iii) the effects of subchronic treatment with antidepressants on FAs in depression. The composition of the FAs was determined by means of thin layer chromatography in conjunction with gas chromatography. Lipid concentrations were assayed by enzymatic colorimetric methods. The oxidative potential index (OPI) of FAs was computed in 34 major depressed inpatients and 14 normal volunteers. Major depression was associated with: increased MUFA and C22:5 omega 3 proportions and increased C20:4 omega 6/C20:5 omega 3 and C22:5 omega 6/C22:6 omega 3 ratios; lower C22:4 omega 6, C20:5 omega 3 and C22:5 omega 3 fractions in phospholipids; lower C18:3 omega 3, C20:5 omega 3 and total (Sigma)omega 3 FAs, and higher C20:4 omega 6/C20:5 omega 3 and Sigma omega 6/Sigma omega 3 ratios in cholesteryl esters; lower serum concentrations of phospholipids and cholesteryl esters; and a decreased OPI. In depression, there were significant and positive correlations between serum Zn and C20:5 omega 3 and C22:6 omega 3 fractions in phospholipids; and significant inverse correlations between serum Zn and the Sigma omega 6/Sigma omega 3, C20:4 omega 6/C20:5 omega 3, and C22:5 omega 6/C22:6 omega 3 ratios in phospholipids. There was no significant effect of antidepressive treatment on any of the FAs. The results show that, in major depression, there is a deficiency of omega 3 PUFAs and a compensatory increase in MUFAs and C22:5 omega 6 in phospholipids. The results suggest that: (i) there is an abnormal metabolism of omega 3 PUFAs in depression; (ii) the FA alterations in depression are related to the inflammatory response in that illness; and (iii) the disorders may persist despite successful antidepressant treatment. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.