Studies of a neurochemical link between depression, anxiety, and stress from [3H]imipramine and [3H]paroxetine binding on human platelets.

We measured platelet [3H]imipramine and [3H]paroxetine binding in patients with major depression (n = 11), dysthymia (n = 9), generalized anxiety (n = 18) and panic disorder (n = 10), and in healthy controls (n = 13). The [3H]imipramine binding capacity (Bmax) was lower in all patient groups; [3H]paroxetine binding was reduced in anxiety disorders, however, decreases in depression and dysthymia were not significant. There were no differences in the affinity constant (Kd) for either radioligand. We also examined the effects of examination stress on platelet binding in medical students. Compared to after vacation, when binding was similar to controls, [3H]imipramine (n = 19) and [3H]paroxetine (n = 14) Bmax values were significantly decreased during examinations and similar to patient values. Examinations were also associated with an increase in plasma cortisol levels. These findings suggest that there is a neurochemical link between depression, anxiety, and stress, and that disturbances in neurochemical functioning may be associated with specific symptomatology, independent of psychiatric diagnosis.