Elevated stress-hemoconcentration in major depression is normalized by antidepressant treatment: secondary analysis from a randomized, double-blind clinical trial and relevance to cardiovascular disease risk

Background

Major depressive disorder (MDD) is an independent risk factor forcardiovascular disease (CVD); the presence of MDD symptoms in patients withCVD is associated with a higher incidence of cardiac complications followingacute myocardial infarction (MI). Stress-hemoconcentration, a result ofpsychological stress that might be a risk factor for the pathogenesis ofCVD, has been studied in stress-challenge paradigms but has not beensystematically studied in MDD.

Methods

Secondary analysis of stress hemoconcentration was performed on data fromcontrols and subjects with mild to moderate MDD participating in an ongoingpharmacogenetic study of antidepressant treatment response to desipramine orfluoxetine. Hematologic and hemorheologic measures ofstress-hemoconcentration included blood cell counts, hematocrit, hemoglobin,total serum protein, and albumin, and whole blood viscosity.

Findings

Subjects with mild to moderate MDD had significantly increased hemorheologicmeasures of stress-hemoconcentration and blood viscosity when compared tocontrols; these measures were correlated with depression severity. Measuresof stress-hemoconcentration improved significantly after 8 weeks ofantidepressant treatment. Improvements in white blood cell count, red bloodcell measures and plasma volume were correlated with decreased severity ofdepression.

Conclusions

Our secondary data analyses support that stress-hemoconcentration, possiblycaused by decrements in plasma volume during psychological stress, ispresent in Mexican-American subjects with mild to moderate MDD atnon-challenged baseline conditions. We also found that after antidepressanttreatment hemorheologic measures of stress-hemoconcentration are improvedand are correlated with improvement of depressive symptoms. These findingssuggest that antidepressant treatment may have a positive impact in CVD byameliorating increased blood viscosity. Physicians should be aware of thepotential impact of measures of hemoconcentration and consider theimplications for cardiovascular risk in depressed patients.