Generalized anxiety disorder: 8 studies of biological interventions

7. Keefe JR, Guo W, Li QS, et al. An exploratory study of salivary cortisol changes during chamomile extract therapy of moderate to severe generalized anxiety disorder. J Psychiatr Res. 2018;96:189-195. doi:10.1016/j.jpsychires.2017.10.011

Dysregulated stress response has been proposed as a mechanism for anxiety.^22,23 Patients with GAD have been reported to have alterations in cortisol levels, specifically lower morning cortisol levels and a less steep diurnal cortisol slope; however, it is not clear how treatment affects these levels. Keefe et al¹⁸ examined whether chamomile therapy in patients with GAD affects cortisol levels.

Study design

• In an 8-week, open-label study, 45 adults who met DSM-IV criteria for GAD received chamomile extract capsules 1,500 mg/d.
• Participants used at-home kits to collect their saliva so cortisol levels could be assessed at 8 am, 12 pm, 4 pm, and 8 pm.
• The GAD-7 was used to assess anxiety symptoms.

Outcomes

• Participants who experienced greater improvements in GAD symptoms had relative increases in morning cortisol levels compared to their baseline levels.
• Participants who experienced greater improvements in GAD symptoms had a greater decrease in cortisol levels throughout the day (ie, greater diurnal slope).

Conclusions/limitations

• Greater improvement in GAD symptoms after treatment with chamomile extract appeared to be correlated with increased morning cortisol levels and a steeper diurnal cortisol slope after awakening, which suggests that treatment of GAD may help improve dysregulated stress biology.
• This study had a small sample size and was not placebo-controlled.

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