Phototherapy increases platelet 3H-imipramine binding in patients with winter depression

The density of platelet 3H-imipramine binding sites (Bmax) was investigated in seven inpatients with winter depression before and after incandescent light treatment and in seven healthy volunteers within a 7-day interval without light exposure. A significantly lower mean Bmax value was found in the depressed patients compared to the controls. After light treatment, parallel to a marked clinical improvement, Bmax increased in each patient and reached or even exceeded the mean values of the controls. These results indicate that in patients with winter depression the decreased Bmax value is state-dependent. The incandescent light treatment has beneficial effect in winter depressives and can influence Bmax values.