Anxiety Predicts Increased MI Risk

By Charles Bankhead
LOS ANGELES, Jan. 7 -- Among older men with no history of coronary disease, anxiety predicts an increased risk of myocardial infarction, irrespective of cardiac risk factors, investigators here found.
The adjusted relative risk of MI associated with each standard deviation increase in anxiety was 1.43 (95% confidence interval: 1.17 to 1.75), Biing-Jiun Shen, Ph.D., of the University of Southern California, and colleagues reported in the Jan. 8 issue of the Journal of the American College of Cardiology.
In addition to overall anxiety, several specific manifestations of anxiety also independently predicted an increased risk of MI, the researchers said.
"The results suggest that moderately elevated anxiety is associated with a modest risk of MI and severe anxiety represents an MI risk that may warrant attention," the authors concluded. "The findings indicate that anxiety not only represents an independent, prospective, and unique risk factor for MI, but may also explain the associations between MI and other psychosocial risk factors observed in earlier studies."
Several psychological conditions, including anxiety, have been associated with the onset of coronary artery disease, independent of conventional CAD risk factors, the authors noted. However, previous studies left a variety of conceptual and methodologic issues unaddressed.
In an effort to explore some of them, the researchers evaluated 735 older men (mean age 60) enrolled in the prospective Normative Aging Study. The men had no history of coronary artery disease or diabetes at baseline.
The investigators assessed anxiety by means of four scales from the Minnesota Multiphasic Personality Inventory: psychasthenia, social introversion, phobia, and manifest anxiety. Overall anxiety was calculated from scores on the four scales.
After a mean follow-up of 12.4 years, anxiety traits independently predicted MI risk after controlling for age, education, marital status, fasting glucose, body mass index, HDL cholesterol, and systolic blood pressure.
The following adjusted relative risks emerged from the analysis:
Psychasthenia, 1.37 (95% CI: 1.12 to 1.68)
Social introversion, 1.31 (95% CI: 1.05 to 1.63)
Phobia, 1.36 (95% CI: 1.10 to 1.68)
Manifest anxiety, 1.42 (95% CI: 1.14 to 1.76)
Overall anxiety, 1.43 (95% CI: 1.17 to 1.75)
The relationships remained significant after further adjustment for health behaviors, use of medications for hypertension, hypercholesterolemia, and diabetes during follow-up, and additional psychological variables.
The authors suggested several potential explanations for the findings:
Associations between anxiety and repeated and chronic elevations of stress
Dysregulation of stress-related pathophysiologic pathways (such as hypothalamic-pituitary-adrenal axis and disturbed platelet activation)
Stimulation of systemic inflammation
Reduced vagal tone and heart-rate variability
The study was performed mainly in otherwise healthy Caucasian men, which limits extrapolation of findings to other groups.
Although anxiety was the strongest predictor of MI risk among psychological variables, the authors cautioned against dismissing other psychological factors, such as depression and hostility.
"Psychological factors are interrelated and may contribute to one another in a reciprocal fashion," they stated. "Recognizing multiple psychosocial risk components may better inform risk assessment and management for people at higher risk for MI."
The study was supported by the American Heart Association and the National Alliance for Research on Schizophrenia and Depression.
The authors reported no conflicts of interest.
Primary source: Journal of the American College of CardiologySource reference:Shen BJ, et al "Anxiety characteristics independently and prospectively predict myocardial infarction in men" J Am Coll Cardiol 2008; DOI: 10.1016/j.jacc.2007.09.033.