Effect of mental and physical stress on platelet activation markers in depressed patients and healthy subjects: a pilot study

Depression represents an independent risk factor for developing ischemic heart disease, with platelet hyperactivity possibly serving as an important mediator of this association. In this pilot study we analyzed platelet surface activation markers in response to two stimuli, mental stress and physical activity. Using flow cytometry, we quantified the presence of two functional activation-dependent glycoprotein receptors on platelets' surface (P-selectin, GP53). Platelet reactivity was assessed as the difference in markers' fluorescence intensity before and after stimulation. We included 10 depressed psychiatric inpatients and 10 age- and sex-matched healthy subjects in our study. There was a significant rise in platelet activation markers in both groups associated with the stress protocol. When the effect of stressors was analyzed separately, strenuous physical activity was found to lead to a significant rise in platelet activition markers in depressed patients but not in healthy subjects, although values indicated a higher baseline level of activation in healthy subjects. These preliminary results lend partial support to the hypothesis of an exaggerated platelet reactivity after physical activity in depression, thus possibly contributing to an increased cardiovascular risk in this disorder. (C) 2004 Elsevier Ireland Ltd. All rights reserved.