Difficult-to-Treat Depressed Patients May Be Bipolar

Clinical experience and limited naturalistic studies have suggested that treatment-refractory depression may be due to unrecognized bipolar disorder. Using a national Taiwanese insurance database of 1 million people, these researchers identified two successive annual cohorts (in 2000 and 2003) of depressed patients, characterized their treatment resistance by the number of different antidepressant trials they received, and related levels of treatment resistance to subsequent change in diagnosis over the next 5 to 8 years to a bipolar disorder (made on at least two occasions by psychiatrists).

The most refractory subgroup (2 antidepressant changes) had a rate of conversion to bipolar diagnosis of roughly 25%. Compared with the conversion rate…