Mechanisms of action in the prevention of recurrent mood disorders

Background: Since long-term treatment is a need in many patients with mood disorders, knowledge on mechanisms of action in the prevention of recurrence is of major relevance. Methods: Follow-up studies, which are best suited to prove the linkage of causal factors and mechanisms with the clinical course of the disorders, are rare. Another approach to search for preventive mechanisms is to address actions of pharmacological agents, which are effective in prophylactic treatment of mood disorders. Studies over the past several years have indicated that intracellular signaling cascades mediate long-term pharmacological effects via modulation of transcription factors and gene expression of neurotrophic and neuroprotective factors which may interfere with recurrence of affective illness. Results: The impact of treatment on stress responsive systems varies with different therapeutic strategies and the relevance of a treatment-related modification of stress reliability for the course of the disease is not clear. Functional and structural actions of mood stabilizers and of antidepressants on mood-relevant anatomical circuits and modulation of chronobiological alteraltions also appear to be involved in preventive mechanisms in mood disorders. Moreover, cognitive mediators of prophylactic effects have been described. Conclusion: Combined clinical and biological studies should assess the relevance of those modes of action for the long-term course of mood disorders.