Bøen E, et al. - Researchers investigated brain glucose metabolism in borderline personality disorder (BPD) patients, bipolar II disorder (BIP-II) patients and healthy control subjects (HCs). Using 2-deoxy-2[18F]-fluoro-d-glucose positron-emission tomography (PET) scanning, they examined 65 subjects, 22 BPD (19 females), 22 BIP-II (17 females), and 21 HC (14 females). Compared with HCs, both patient groups displayed hypometabolism in insula, brainstem, and frontal white matter, indicating shared pathophysiological mechanisms. Additionally, differential pathophysiology was suggested by the observed patterns of altered metabolism specific to each patient group, as well as the uncorrected results. Hypometabolism was observed in hypothalamus, midbrain, and striatum in BPD patients and in cerebellum in BIP-II patients. As per uncorrected analyses, there were cortical areas of higher metabolism in BIP-II than BPD, and associations with clinical variables differed between the groups.