ients with bipolar disorder? The rate of bipolar disorder diagnoses has increased notably in the past 15 years (Moreno C et al., Arch Gen Psychiatry 2007;64:1032-1039). In a recent report, researchers looked at data from a study of patients in a community-based outpatient setting (Zimmerman M et al., J Clin Psychiatry;69:935-940) to see whether symptoms of borderline personality disorder increased a per- son’s risk of being misdiagnosed with bipolar disorder. Researchers asked 700 patients if they had ever been diagnosed with bipolar disor- der. One hundred and forty five responded that they had, but a diag- nostic interview confirmed bipolar disorder in only 63 patients (43.4%), meaning that over half of these patients (56.5%) had been falsely diagnosed as bipolar. Because there is substantial overlap between symptoms of borderlinePD and bipolar disorder, the researchers then focused on 52 patients diagnosed with borderline PD. They found that a significantly higher percentage had been misdi- agnosed with bipolar disorder (40%) when compared to those with disorders other than borderline PD (10%). Interestingly, misdiagnoses of bipolar increased with the number patient had, but this trend ceased when a patient met seven or more criteria (suggesting that at this point it is clear the patient has borderline PD and thus not misdiagnosed as bipolar disorder). (Ruggero CJ et al., J Psychiatr Res online aheadof print).