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Clinical depression and inflammatory risk markers for coronary heart disease
Gregory E Miller1, Cinnamon A Stetler, Robert M Carney
1Department of Psychology, Washington University, St. Louis, Missouri 63130, USA. gemiller@arsci.wustl.edu
Insights
Psychiatric depression is linked to higher levels of inflammatory markers, increasing the risk of heart disease. Increased body mass in depressed individuals partially explains this association.
Area of Science:
- Cardiovascular Health
- Psychiatric Research
- Inflammation Biology
Background:
- Psychiatric depression is a known risk factor for cardiac morbidity and mortality.
- The underlying mechanisms linking depression to heart disease remain poorly understood.
- Inflammatory risk markers are implicated in the pathogenesis of coronary heart disease (CHD).
Purpose of the Study:
- To investigate the relationship between depression and the expression of inflammatory risk markers.
- To identify potential mediating pathways, such as adiposity, smoking, or infections, in this association.
Main Methods:
- A study involving 100 healthy adults (50 with clinical depression, 50 matched controls).
- Measurement of inflammatory markers: C-reactive protein (CRP) and interleukin-6 (IL-6).
- Mediational analyses to assess the roles of body mass, smoking, and subclinical infections (cytomegalovirus, Chlamydia pneumoniae).
Main Results:
- Depressed subjects showed significantly higher levels of CRP and IL-6 compared to controls.
- Neither smoking nor subclinical infections mediated the observed association.
- Increased body mass (adiposity) was found to account for a portion of the link between depression and heightened inflammation.
Conclusions:
- In healthy adults, depression is associated with increased expression of inflammatory markers relevant to CHD pathogenesis.
- Adiposity partially mediates the relationship between clinical depression and elevated inflammatory markers.
- Further research is needed to fully elucidate the complex interplay between depression, inflammation, and cardiovascular health.
Abstract:
Despite mounting evidence that psychiatric depression heightens risk for cardiac morbidity and mortality, little is known about the mechanisms responsible for this association. The present study examined the relation between depression and the expression of inflammatory risk markers implicated in the pathogenesis of coronary heart disease (CHD). One hundred adults were enrolled (68% women, 48% Caucasian, 48% African-American, mean age 30 +/- 2 years). Fifty subjects met the diagnostic criteria for clinical depression; the remaining 50 were demographically matched controls with no history of psychiatric illness. All subjects were in excellent health, defined as having no acute infectious disease, chronic medical illness, or regular medication regimen aside from oral contraceptives. The depressed subjects exhibited significantly higher levels of the inflammatory markers C-reactive protein (3.5 +/- 0.5 vs 2.5 +/- 5 mg/L, p = 0.04) and interleukin-6 (3.0 +/- 0.3 vs 1.9 +/- 0.2 pg/ml, p = 0.007) compared with control subjects. Mediational analyses aimed at identifying the pathways contributing to this association revealed that neither cigarette smoking nor subclinical infection with cytomegalovirus or Chlamydia pneumoniae had been responsible. However, depressed subjects exhibited greater body mass than control subjects, and analyses were consistent with adiposity accounting for a portion of the relation between clinical depression and increased expression of inflammatory markers. These findings indicate that in otherwise healthy adults, depression is associated with heightened expression of inflammatory markers implicated in the pathogenesis of CHD. Increased body mass appears to be partially, although not completely, responsible for this relation.