Abstract
Subthreshold psychiatric disorders do not fully meet the diagnostic criteria of syndromal disorders but may be associated with comparable disability. To investigate the anxiolytic effect of Silexan, an active substance from lavender oil for oral administration, in patients with subthreshold anxiety, a meta-analysis that included all published trials with Silexan in this indication was performed. Three randomised, placebo-controlled trials in subthreshold anxiety disorders (anxiety disorder not otherwise specified, restlessness and agitation, mixed anxiety and depressive disorder) were included. Eligible participants with a baseline Hamilton Anxiety Rating Scale (HAMA) total score ≥ 18 points received 1 × 80 mg/day Silexan or placebo for 10 weeks. Outcomes included the HAMA, the Pittsburgh Sleep Quality Index, the Zung Self-rating Anxiety Scale, the Clinical Global Impressions questionnaire and the SF-36 health status inventory. Data were analysed using meta-analysis based on pooled raw data of individual patients (random effects models). A total of 697 patients were assessed for efficacy. Silexan was superior to placebo in reducing the HAMA total score during 10 weeks’ treatment [mean value difference, 95% confidence interval: 3.83 (1.28; 6.37) points]. Superiority was comparably pronounced for psychic and somatic anxiety as well as for observer- and self-rated anxiety. Silexan had a beneficial effect on sleep (secondary to the anxiolytic effect) without causing sedation and improved the patients’ health-related quality of life. Adverse event incidence in both treatment groups was comparable [risk ratio: 1.06 (0.85; 1.33)]. Silexan has a significant and clinically meaningful anxiolytic effect in subthreshold anxiety. The results cannot be generalised to other lavender oil products.
Highlights
Subthreshold anxiety disorder (SSAD, subsyndromal anxiety disorder) is a very common but often underdiagnosed and undertreated condition that refers to Epidemiological data suggest that the population prevalence of SSAD may exceed that of generalised anxiety disorder (GAD) in Europe and North America by a factor of about three [1,2,3]
Silexan, which has been licensed in 14 countries worldwide and is the active substance of a medicinal product marketed in Germany, is produced from lavender and causes a potent inhibition of voltage dependent calcium channels (VOCCs) in synaptosomes, primary hippocampal neurons and stably overexpressing cell lines [10], which have been shown to play an important role in both anxiety and depression
Our meta-analysis demonstrates that Silexan is superior to placebo in reducing the anxiety-associated symptoms in patients suffering from SSAD, including MADD or restlessness and agitation disorder
Summary
Subthreshold anxiety disorder (SSAD, subsyndromal anxiety disorder) is a very common but often underdiagnosed and undertreated condition that refers to Epidemiological data suggest that the population prevalence of SSAD may exceed that of GAD in Europe and North America by a factor of about three [1,2,3]. There is almost uniform agreement between researchers that SSAD causes relevant functional impairment and suffering, has a detrimental effect on quality of life, is associated with a high level of co-morbidity and bears a considerable risk of exacerbation to threshold anxiety, mood disorder or substance use disorders [1, 5, 6]. SSAD, in contrast to GAD, was found to be associated with a significant decrease in perceived social support [7]. These findings underline the need for an early and adequate treatment of SSAD, which could efficiently and cost-effectively prevent a progression to the syndromal level [8, 9]. Silexan significantly reduces the 5-HT1A binding potential in the brain clusters encompassing the temporal gyrus, the fusiform gyrus, the hippocampus, the insula and the anterior cingulate cortex, which may lead to an increase of extracellular serotonin levels [12]
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