Partial or non-response to antidepressants in Generalized Anxiety Disorder (GAD) is common in clinical settings, and adjunctive biological interventions may be required. Adjunctive herbal and nutraceutical treatments are a novel and promising treatment option. L-theanine is a non-protein amino acid derived most-commonly from tea (Camellia sinensis) leaves, which may be beneficial in the treatment of anxiety and sleep disturbance as suggested by preliminary evidence. We conducted a 10-week study (consisting of an 8-week double-blind placebo-controlled controlled period, and 1-week pre-study and 2-week post-study single-blinded observational periods) involving 46 participants with a DSM-5 diagnosis of GAD. Participants received adjunctive Ltheanine (450-900mg) or matching placebo with their current stable antidepressant treatment, and were assessed on anxiety, sleep quality, and cognition outcomes. Results revealed that adjunctive L-theanine did not outperform placebo for anxiety reduction on the HAMA (p = 0.73) nor insomnia severity on the Insomnia Severity Index (ISI; p = 0.35). However, LT treated participants reported greater self-reported sleep satisfaction than placebo (ISI item 4; p = 0.015). Further, a separation in favour of L-theanine was noted on the ISI in those with non-clinical levels of insomnia symptoms (ISI ≤ 14; p = 0.007). No significant cognitive effects (trail making time and the modified emotional Stroop) were revealed. While this preliminary study did not support the efficacy of L-theanine in the treatment of anxiety symptoms in GAD, further studies to explore the application of L-theanine in sleep disturbance are warranted.

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Study Objectives The aim of this study was to test the efficacy and safety of Zao Ren An Shen (ZRAS) capsule, a Chinese herbal medicine product, for the treatment of insomnia. Methods We conducted a double-blind randomized placebo-controlled trial. After a one-week placebo run-in, a total of 85 people with insomnia were randomly allocated to receive ZRAS or placebo for 4 weeks. The primary outcomes were insomnia severity assessed with the Insomnia Severity Index (ISI) and the number of participants with adverse events (AEs). Secondary outcomes included objective and subjective sleep parameters, psychological status, fatigue level, quality of life, acceptability, and tolerability. Results A nonsignificant (p > .05) difference of 0.7 points in ISI in favor of ZRAS capsule was found at the end of the treatment. The number of participants with AEs was not significantly different (p > .05) between the two groups. Except for subjective sleep onset latency, which had a nonsignificant (p > .05) medium effect (Cohen’s d = 0.5), the effects in secondary efficacy outcomes were all small (Cohen’s d < .4) and nonsignificant (p > .05). The acceptability and tolerability were high in the active group. Conclusions ZRAS capsule is safe, acceptable, and tolerable, yet not more effective than placebo in the treatment of insomnia. As previous evidence showed that Chinese herbal medicine was effective for insomnia, these results may be explained by the dose of the product, which was lower than the dose generally used in the clinic. Registration: This clinical trial was registered in Australia New Zealand Clinical Trial Registry (registration number ACTRN12619000140156) under the name “Impact of Zao Ren An Shen (ZRAS) capsule on chronic insomnia patients’ insomnia severity: A randomized-controlled trial” (https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376730&isReview=true).

The design of a CBTI program adapted to Chinese population was achieved. Culturally adapted CBTI showed promising results. More rigorously designed studies are needed to ensure efficacy.