Objective-Fibrosis plays an important role in heart failure (HF) and other diseases that occur more frequently with increasing age. Depression is associated with an increased risk of heart failure and other age-related diseases. This study examined the association between depressive symptoms and fibrosis markers in adults aged 65 years and above.Methods-Fibrosis markers and depressive symptoms were assessed in 870 participants (age=80.9 ±5.9, 49% women) using a case-control design based on heart failure status (307 HF patients and 563 age-and sex-matched controls, of whom 284 with CVD risk factors (hypertension, diabetes mellitus, or hypercholesterolemia) and 279 controls without these CVD risk factors). Fibrosis markers were procollagen type I (PIP), type I collagen (CITP), and procollagen type III (PIIINP). Inflammation markers included C-reactive protein, white blood cell counts and fibrinogen. Depression was assessed using the Center for Epidemiological Studies-Depression (CES-D) scale using a previously validated cut-off point for depression (CES-D ≥ 8). Covariates included: demographic and clinical variables.Results-Depression was associated with higher levels of PIP (median=411.0, inter quartile range (IQR)=324.4-472.7 ng/mL vs. 387.6, IQR=342.0-512.5 ng/mL, p=0.006) and CITP (4.99, vs. 4.53,.22 μg/L, p=0.024), but not PIIIINP (4.07, IQR = 2.75-5.54 μg/mL vs. 3.58, IQR=2.71-5.01 μg/mL, p=0.29) compared to individuals without depression. Inflammation markers were also elevated in depressed participants (CRP, p=0.014; WBC, p=0.075; fibrinogen, p=0.074), but these inflammation markers did not account for the relationship between depression and fibrosis markers.Conclusions-Depression is associated with elevated fibrosis markers and may therefore adversely affect heart failure and other age-related diseases in which extra-cellular matrix formation plays a pathophysiological role.Corresponding Author: Willem J. Kop, University of Maryland Baltimore, 22 South Greene Street, Ste. 3B08, Baltimore, MD 21201, Phone: 410-328-2063, FAX: 410-328-4382, wkop@medicine.umaryland.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Fibrosis contributes to cardiovascular disease progression in general and heart failure in particular. Myocardial fibrosis and subsequent cardiac remodelling occurs in heart failure because of increased collagen production and collagen deposition as a result of pressure overload, myocardial ischemia, as well as neurohormonal activation (including the reninagiotensin-aldosterone axis and sympathetic nervous system activation) (Gonzalez et al., 200...