TRH stimulation and dexamethasone suppression in borderline personality disorder

The link between borderline personality disorder (BPD) and affective disorders is controversial. The dexamethasone suppression test (DST) and the thyrotropin-releasing hormone (TRH) stimulation test, which are useful in the study of affective illness, might help to elucidate this possible link. This report assessed these endocrine tests in a sample of 20 borderline patients without a concomitant diagnosis of major depression (but showing depressive symptoms) in comparison to a group of sex- and age-matched patients with major depressive disorder (MDD) without BPD. Only 5 of our BPD patients were DST nonsuppressors compared to 13 MDD patients at a threshold of 50 μg/L. With a threshold of Δmax TSH < 5μU/mL following TRH, 1 BPD patient showed a blunted TSH response compared to 9 MDD patients. BPD patients displayed significantly less perturbed tests. These results show no evidence of an endocrine biological link between BPD and the MDD. The depressive symptoms observed in BPD patients might not have the same biological substrates as those found in patients with MDD.