[Electroconvulsive therapy in depression: insights from fMRI, PET and SPECT studies]

Electroconvulsive therapy (ECT) is the most potent and rapidly acting of all antidepressant treatments in major depressive disorder (MDD). Nuclear and functional magnetic (fMRI) brain imaging studies of ECT have substantially contributed to the neurobiological understanding of this treatment modality. Neuroimaging methods may also validate potential mechanisms of antidepressant action. Models of neural dysfunction in MDD suggest impaired modulation of activity within a cortico-limbic circuitry, along with alterations in the functional organisation of multiple brain networks implicated in emotional processes. Nuclear imaging techniques have demonstrated consistent patterns of ECT-induced ictal changes in brain activity that appear to be linked to efficacy and side effects of ECT. Interictally, widespread alterations of brain function have been reported, however, results remain inconclusive. FMRI studies of ECT have demonstrated longer-lasting, interictal changes of neural activity in multiple cerebral regions that are in accordance with functional neuroanatomical models of mood disorders. Future research detailing ECT interactions with brain pathophysiology in MDD could potentially provide a clinically useful framework to better predict ECT treatment response and/or side effects, and may also facilitate the development of more focused brain stimulation techniques.