Platelet supersensitivity to thrombin stimulation in depression: A possible mechanism for the association with cardiovascular mortality

The mortality risk associated with cardiovascular disease is significantly increased in patients with major depression and panic disorder. The mechani sm of this phenomenon is unclear. Thrombin is responsible for platelet aggr egation and shape change, and it plays a significant role in the developmen t of thromboembolic events. In this study, we examined the platelet second messenger intracellular calcium response to thrombin stimulation in patient s with major depression (n = 13), major depression after response to electr oconvulsive therapy( ECT; n = 13), subsyndromal depression (n = 16), schizo phrenia (n = 15), and control subjects (n = 65). Patients with major depres sion had significantly higher intracellular calcium responses to thrombin s timulation than control subjects, patients with subsyndromal depression, an d patients with schizophrenia (p < 0.05). Electroconvulsive therapy did not significantly change this supersensitivity. This suggests that the platele t response to activation in patients with major depression is supersensitiv e. This study suggests a possible mechanism for the increased risk of cardi ovascular disease that is seen in these two psychiatric disorders. The lack of difference between the control and subsyndromal depression groups appea rs to validate current diagnostic thresholds in depression. The failure of nonpharmacologic treatment to alter this marker suggests that it may be a t rait marker of depression.