[Atypical depression and related illnesses--neurobiological principles for their treatment with Hypericum extract].

Atypical depression, somatoform disorder, neurasthenia and fibromyalgia seem to form a spectrum of disorders, who share a common biological basis, i.e. a reduced activity of the hypothalamus-pituitary-adrenocortical (HPA)-system. This is similar to the situation in Cushing's disease, where the central part of the hypothalamus-pituitary-adrenocortical-system is decreased by an increased feedback via increased intracerebral cortisol concentration. Cushing's disease is accompanied by features of atypical depression and of somatisation. Treatment with hypericum seems to disinhibit the hypothalamus-pituitary-adrenocortical-system in healthy subjects and patients with a depression. Furthermore it decreases intracerebral corticosteroids, possibly by increasing the expression of p-glycoprotein at the blood brain barrier. Therefore hypericum might be especially effective in patients with a symptom cluster of atypical depressive features and somatisation. Clinical studies with patients with depression with atypical features like the seasonal affective disorder (SAD) and with patients with a depressive syndrome accompanied by somatic complaints or fatigue support this view.