The original declaration of interest for this article wrongly implied that Andrea Cipriani (A.C.) had received fees for lecturing from the pharmaceutical companies Lundbeck and Sunovion. This was an accidental duplication of the declaration of interest by Anthony J. Cleare (A.J.C.) which immediately follows it.
Andrea Cipriani has no conflict of interest and nothing to declare.
The article has been updated with an explanatory note.
Keywords: Treatment resistant, bipolar disorder, depression, definition, consensus, corrigendum