Abstract
Objectives: This exploratory analysis examined the putative antidepressant effect of Matricaria chamomilla L. (chamomile) extract in subjects with generalized anxiety disorder (GAD) with or without comorbid depression. It was hypothesized that chamomile extract would demonstrate similar anxiolytic activity in both subgroups, but superior antidepressant activity in GAD subjects with comorbid depression. Design: As part of a randomized double-blind placebo-controlled trial of chamomile extract for relapse prevention of GAD, 179 subjects received initial therapy with open-label chamomile extract 1500 mg daily for 8 weeks. Linear mixed-effect models were used to identify clinically meaningful changes in anxiety and depression symptoms between diagnostic subgroups. Settings/Location: The study took place at the University of Pennsylvania in Philadelphia, PA. Subjects: Subjects were ≥18 years old with a primary DSM IV-TR diagnosis of GAD. They were subcategorized into two diagnostic groups: GAD without comorbid depression (n = 100) and GAD with comorbid depression (n = 79). Interventions: Open-label chamomile extract 1500 mg was given daily for 8 weeks. Outcome measures: Generalized anxiety disorder (GAD-7), Hamilton rating scale for anxiety, Beck anxiety inventory, Hamilton rating scale for depression (HRSD), the six-item core HRSD (items 1, 2, 3, 7, 8, and 13), and the Beck depression inventory (BDI). Results: The authors observed similar anxiolytic effects over time in both diagnostic subgroups. However, there was a greater reduction in HRSD core symptom scores (p < 0.023), and a trend level reduction in HRSD total scores (p = 0.14) and in BPI total scores (p = 0.060) in subjects with comorbid depression. Conclusions: M. chamomilla L. may produce clinically meaningful antidepressant effects in addition to its anxiolytic activity in subjects with GAD and comorbid depression. Future controlled trials in subjects with primary major depressive disorder are needed to validate this preliminary observation.