EEG sleep, lithium transport, dexamethasone suppression, and monoamine oxidase activity in borderline personality disorder.

Twenty-one patients who met DSM-III criteria for borderline personality disorder (BPD) and also scored at least 7 on the Diagnostic Interview for Borderlines (DIB) were assessed on four biological markers: electroencephalographic (EEG) sleep, in vitro lithium ratio, platelet monoamine oxidase (MAO), and dexamethasone suppression test (DST). REM latency averaged 58.66 (SD 14.39); platelet MAO averaged 21.74 (SD 10.33); and lithium ratio was 0.357 (SD 0.139) in the BPD patients. All of those values were significantly abnormal. Many patients had abnormalities on three or four measures. These patients in general had multiple Axis I diagnoses from the Diagnostic Interview Schedule (DIS), and these Axis I diagnoses tended to produce patient clusters. Patients with a DIS diagnosis of schizophrenia, mania, hypomania, or schizoaffective mania had elevated lithium, low MAO, and normal EEG sleep, while those patients with coexisting major depression tended to have short rapid eye movement (REM) latency, high REM density, and normal MAO and lithium ratio. Only two patients were nonsuppressors on the DST, confirming recent reports of normal DST results in personality disorders.