Aims: This work would give an overall vision of the actual knowledge about nosography and clinic of treatment-resistant depression.
Method: A PubMed, PsychInfo, Google Scolar search was done using the key words "resistant depression", "STAR*D", "bipolar depression", "staging". Have been selected exclusively works in English, French and Italian languages.
Results: Treatment-resistant depression is one of the most important problem in public health. Nevertheless a general consensus about its definition and staging does not exist at now. Principal risk factors and associated comorbidities are well known including the association with bipolar spectrum; anyway the disease particularly common among depressed outpatients is still very disabling, responsible of an often chronic course, with numerous relapses and high risk of suicide.
Discussion and conclusion: The future investigations, once improved procedures for differential diagnosis and subtyping of clinical depression, should be directed to the search of a shared definition of treatment resistance and the development of specific therapeutic protocols.