AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 48:182–193 (2005) Job Strain and Autonomic Indices of Cardiovascular Disease Risk Sean M. Collins, PT , ScD, CCS, 1 Robert A. Karasek, PhD, 2 and Kevin Costas, MPH 2 Background Despite the epidemiological evidence linking job strain to cardiovascular disease, more insight is needed into the etiologic mechanisms. This, in turn, would help to more precisely identify risk. Methods We measured Job Strain using the Job Content Questionnaire, 8/day diary reports, and nationally standardized occupational code linkage, as well as autonomic regulation utilizing heart rate variability including spectral-derived components and QT interval variability in 36 healthy mid-aged males with varying strain jobs. The subjects wore Holter-monitors for 48 hr; this included a work and rest day. Results Job strain (P ¼ 0.02) and low decision latitude (P ¼ 0.004) were associated with a reduction in cardiac vagal control (HFP) persisting throughout the 48 hr. Job strain was also associated with elevations in sympathetic control during working hours (P ¼ 0.003). Conclusions The disturbed cardiovascular regulatory pattern associated with job strain may help explain the increased risk of cardiovascular diseases linked with occupational exposure. Am. J. Ind. Med. 48:182 – 193, 2005. ß 2005 Wiley-Liss, Inc. KEY WORDS: job strain; heart rate variability; job content questionnaire; psychosocial factors; occupational stress; cardiac disease risk INTRODUCTION Substantial research now exists relating adverse psy- chosocial work environments to cardiovascular disease, with a recent comprehensive review of 46 studies concluding: ‘‘the strong, consistent evidence of an association ...support the conclusion that job strain is indeed a major CVD risk factor’’ [Schnall et al., 1998; Belkic et al., 2004]. The public policy implications of confirming ‘‘work-relatedness’’ are significant since cardiovascular disease remains the leading cause of mortality and morbidity in industrialized countries. Indeed, the recent Korean practice [KOSHA, 1998] of clas- sifying significant portions of cardiovascular illness as work- related has elevated heart disease to one of the two primary causes of work-related mortality in Korea. Gaps remain in this research, however, notably: there is less research on the specific physiological pathways of disease causation [Schnall et al., 1994, 2000], although failures in blood pressure regulation, when assessed by ambulatory monitor- ing, are clearly identified [Schnall et al., 1998]. We assess whether regulatory limitations of nervous system control (sympathetic and parasympathetic autonomic) could be one of the important pathways by which psychosocial risks contribute to cardiovascular illness. These limitations, if confirmed, could implicate work stress in the broad range of other diseases affected by autonomic nervous system (ANS) regulation. The demand control model (or demand/control/support model) is perhaps the most commonly utilized hypothesis associating psychosocial factors at work with cardiovascular ß 2005 Wiley-Liss, Inc. 1 Department of Physical Therapy, School of Health and Environment, University of Massachusetts,Lowell, Massachusetts 2 Department of Work Environment, School of Health and Environment, University of Massachusetts,Lowell, Massachusetts Institution where work was performed: Department of Work Environment, School of Health and Environment, University of Massachusetts Lowell. Contract grant sponsor: Chancellor’s Research Fund; Contract grant sponsor: Kerr Ergo- nomics Institute; Contract grantsponsor:Department of Work Environment, School of Health and Environment, University of Massachusetts Lowell. *Correspondence to: Sean M. Collins, School of Health and Environment, University of Massachusetts Lowell, 3 Solomont Way, Suite 5, Lowell, MA 01854-5124. E-mail: Sean__Collins@uml.edu Accepted 24 June 2005 DOI10.1002/ajim.20204. Published online in Wiley InterScience (www.interscience.wiley.com)