LONDON, UNITED KINGDOM. The incidence of metabolic syndrome (syndrome X, insulin resistance syndrome) is growing rapidly in the Western world. The syndrome is increasingly viewed as an important precursor of atherosclerosis and coronary disease. The syndrome consists of a cluster of common symptoms including insulin resistance, abdominal obesity, hypertension (high blood pressure), high triglyceride levels, and low levels of "good" cholesterol (HDL cholesterol).
British researchers have discovered that there is a strong connection between a dysfunctional autonomic nervous system, stress hormone levels, and the metabolic syndrome (MS). Their study involved 30 working men between the ages of 45 and 63 years who had been diagnosed with MS and 153 matched, healthy controls. The researchers found that the men with MS had significantly higher levels of cortisol (urinary metabolites) and normetanephrine (a metabolite of norepinephrine). They also had a higher heart rate, lower heart rate variability, and an autonomic nervous system balance that was significantly tilted towards sympathetic (adrenergic) predominance. The MS patients also had significantly higher levels of the inflammation markers interleukin-6 and C-reactive protein. The viscosity of their blood plasma was also significantly higher than that of the controls and their level of urinary epiandrosterone (a metabolite of dehydroepiandrosterone [DHEA]) tended to be lower than that of the controls.
The researchers conclude that their findings point to a clear association between metabolic syndrome and long-term stress. They estimate that about 37% of the risk of developing MS can be attributed to high norepinephrine level (excessive sympathetic activity). Their findings, they believe, may go a long way towards explaining why men at a low socioeconomic level (more stress) have a much higher risk of coronary heart disease than do men in a more "comfortable" socioeconomic position.
Dr. Paul Hjemdahl, MD, PhD of the Karolinska Hospital and Institute in Stockholm commented on the new findings. He agrees that an autonomic nervous system imbalance plays a large part in the development of MS and suggests that weight loss, exercise, and dietary modifications may help prevent it. He also suggests that psychosocial intervention to reduce stress and improve working conditions (reduce inappropriate demands and improve job satisfaction and control) and social support may help prevent MS. Says Dr. Hjemdahl, "Society faces a tough challenge regarding the metabolic syndrome and its medical consequences in the future."
Brunner, EJ, et al. Adrenocortical, autonomic, and inflammatory causes of the metabolic syndrome. Circulation, Vol. 106, November 19, 2002, pp. 2659-65
Hjemdahl, P. Stress and the metabolic syndrome. Circulation, Vol. 106, November 19, 2002, pp. 2634-36 (editorial)