background Studies have indicated an association between treatment refractoriness in unipolar depression and unrecognised bipolar spectrum disorder (bsd). If confirmed, this may have implications for diagnosis and treatment.
aim To provide an overview on the prevalence and recognition of bsd in treatment resistant depression (trd).
method A search was made in PubMed concerning the prevalence of bsd in trd and clinical features that may be suggestive of bipolar depression.
results Three articles were found that examined the prevalence of bsd in trd; they reported that 26-47% of patients with trd had an underlying bsd. Five cross-sectional studies described the predictors of clinical features in patients with a major depression. The following features occurred significantly more often: positive family history of bsd, young age of onset, higher number of recurrences, and atypical features.
conclusion There seems to be an association between trd and having an underlying bsd. A few clinical features may help to detect bsd in trd.