Sustained Low-Grade Pro-inflammatory State in Unmedicated, Remitted Women with Major Depressive Disorder as Evidenced by Elevated Serum Levels of the Acute Phase Proteins C-reactive Protein and Serum Amyloid A

Background Major depressive disorder (MDD) shows increased coronary artery disease (CAD) risk of unknown mechanism(s). MDD is more common in women than men; CAD diagnosis can be difficult in women. Elevations of the inflammatory markers C-reactive protein (CRP) and serum amyloid A (SAA) predict increased CAD risk in populations; few data on these markers exist in MDD, particularly in remitted patients. Methods We measured fasting am serum CRP (high sensitivity, CRPhs) and SAA in 18 unmedicated, remitted women with MDD (mean age 41 ± (SD)12, body mass index (BMI) 25.2 ± 4.1 kg/m2) and 18 BMI-matched healthy control subjects (age 36 ± 10, BMI 25.3 ± 3.8 kg/m2) on 2 separate occasions, ≥ 6 days apart. Results Repeat SAA and CRPhs measurements strongly correlated across study days (SAA: r = .83, p< .001; CRPhs: r = .94, p< .001). Both SAA (5.30 ± 3.39 vs. 2.84 ± 1.87 mg/L, p< .005) and CRPhs (3.23 ± 3.17 vs. 1.12 ± 1.45 mg/L; p< .01) were significantly elevated in MDD women versus controls. Conclusions Elevated SAA and CRPhs in remitted, unmedicated women with MDD indicate a pro-inflammatory state unrelated to current depressive symptoms or pharmacotherapy. These findings suggest that inflammatory mechanisms may in part underlie findings of increased CAD risk in MDD.