Abstract 2421: Major Depression is Associated with Elevated Levels of Serum Myeloperoxidase
Introduction: Depression is a risk factor for CAD; both inflammation and oxidative stress have been proposed as potential mechanisms. Myeloperoxidase (MPO), a leukocyte enzyme that promotes free radical production, is involved in the etiology of coronary artery disease (CAD) and is elevated in CAD patients. However, it is not known whether MPO is related to depression.
Methods: We examined 204 monozygotic (MZ) and 156 dizygotic (DZ) male twins (180 pairs) from the Vietnam Era Twin Registry who were born between 1946 and 1956. History of major depressive disorder (MDD) was measured with the Structured Clinical Interview for Psychiatry Disorders. Serum MPO was measured by high-sensitivity sandwich ELISA and data were log-transformed for analysis. Mixed effects regression was used to account for twin pairs and estimate within- and between-pair effects.
Results: The mean age of the twins was 54 yrs; 34% had hypertension, 41% hyperlipidemia, 9% diabetes, 10% previous CAD, 38% were obese (BMI≥30) and 20% smoked. The prevalence of MDD was 23% and 68 pairs were discordant for MDD. Twins with MDD had 33% higher levels of MPO (799 vs. 602 pmol/L, p<0.0001) compared to twins without MDD. This difference decreased slightly to 28% (p=0.0002) after adjusting for traditional CAD risk factors and previous CAD. Among discordant pairs, twins with MDD had 35% higher MPO than their brothers without MDD after adjusting for other factors (p=0.0005). However, the difference was much larger in DZ (64%, p=0.0001) than in MZ twins (14%, p=0.14), with a significant MDD-zygosity interaction (p=0.03), suggesting a genetic influence on the association. Exclusion of subjects with previous CAD did not change the results.
Conclusion: Major depression is associated with higher serum MPO independent of CAD risk factors. This association is due, in part, to a shared genetic substrate between depression and inflammation.