Stress and cardiovascular disease.

Abstract

The statistical associations between stress and cardiovascular and other prevalent diseases have not been explained. Perceived stress, resulting in an uncontrollable defeat reaction, has been shown by James Henry (Henry 1993) to be followed by specific endocrine abnormalities, including sensitization of the hypothalamo-pituitary-adrenal (HPA) axis, and inhibited sex steroid and growth hormone secretions. With an elevated waist/hip circumference ratio (WHR)--a simple, surrogate, measurement of intraabdominal, visceral fat masses--combined with insulin resistance, similar endocrine perturbations are found. Based on considerable evidence, such endocrine abnormalities seem to be followed by accumulation of intraabdominal, visceral fat masses and insulin resistance, both powerful risk factors for cardiovascular disease, diabetes and stroke. A postulated chain of events is therefore that the endocrine perturbations are primary factors, followed by visceral fat accumulation, insulin resistance and other risk factors dependent on the hyperinsulinemia following insulin resistance. This highlights the importance of elucidating the cause(s) to the endocrine abnormalities. These are identical to those described by Henry (1993) to follow a stress reaction of a defeat type. Findings of several psychosocial and socio-economic handicaps might provide a basis for such a reaction, supported by experimental studies in primates. Furthermore, depression, anxiety, alcohol consumption and smoking, all known activators of the HPA axis, are also often found. The low sex steroid and growth hormone secretions might be secondary to the hypersensitive HPA-axis. They could also be caused by other factors, and are, each alone, capable of causing both visceral fat accumulation and insulin resistance. Visceral fat accumulation is only an indirect, surrogate measurement of the underlying endocrine abnormalities, but is useful for screening purposes on a population basis. Developments of novel techniques for sensitive, yet simple measurements of HPA axis activity under undisturbed conditions seem to allow a better definition of pathogenetic factors. Utilizing such methods, subgroups of the syndrome including visceral fat accumulation, insulin resistance and other associated risk factors (Metabolic Syndrome), are beginning to emerge. A more detailed information on noxious factors in society leading to a defeat reaction to perceived stress, endocrine abnormalities and the Metabolic Syndrome, with increased risk for prevalent disease may hopefully be developed by these new methods.