Alpha-1-acid glycoprotein in major depressive disorder - Relationships to severity, response to treatment and imipramine plasma levels

Background: Increased plasma levels of alpha-1-acid glycoprotein (AGP) were reported in major depressive disorder. However, the relationship between A GP levels, severity of depression, treatment response and antidepressant le vels are still unclear. Methods: Plasma AGP levels were measured in 36 subj ects with major depressive disorder before and after a 6-week treatment wit h imipramine and in 30 controls. Free imipramine plasma levels of depressed patients were measured at 6 weeks. Comparative analysis between depressed patients and controls, between non-responders (N = 12) and responders (N = 24), and between severely depressed patients (N = 14) and moderately depres sed patients (N = 22) were made. Results: Depressed patients had significan tly higher mean values of AGP than control subjects. Imipramine non-respond ers and specially severely depressed patients had significantly greater inc reases of AGP levels during treatment than other depressed subgroups. There was no correlation between baseline AGP levels and severity of depression or free imipramine levels. Limitations: The most significant limitations of this study are the small sample size and the fact that all the subjects we re out-patients. Results should not be generalized to in-patient population s. Conclusions: Depressed patients showed high baseline concentrations of A GP. AGP levels did not predict either free imipramine plasma levels or diff erential response after 6 weeks of treatment with imipramine. A greater inc rease of AGP during treatment was associated with severity of depression an d treatment non-response. Clinical implications: The relationship between h igh plasma levels of AGP, severity of depression and lack of treatment resp onse is clarified. The influence of imipramine levels is minimized. (C) 200 0 Elsevier Science B.V. All rights reserved.