Reviewed: Jahanbakhsh SP, Manteghi AA, Emami SA, et al. Evaluation of the efficacy of Withania somnifera (ashwagandha) root extract in patients with obsessive-compulsive disorder: a randomized double-blind placebo-controlled trial. Complement Ther Med. 2016;27:25-29.

Obsessive-compulsive disorder (OCD), characterized by stressful, repetitive, and intrusive thoughts or obsessions followed by actions or compulsions, is thought to be linked to a defect in the serotonergic system. Selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat OCD, but they are considered only mildly effective, with a reported 40-60% of patients failing to respond. Those who do respond to SSRI treatment tend to show only minor improvements in OCD symptoms.

In traditional Ayurvedic herbal medicine, ashwagandha (Withania somnifera, Solanaceae) is considered a rejuvenating and revitalizing herb. Its roots, which are used to enhance mental and physical health, have anxiolytic and antidepressant properties and have been used in the treatment of nervous disorders. The phytochemicals thought to play a role in these therapeutic effects include bioactive steroids (withanolides and withanolide glycosides) and alkaloids (withanine and somniferine). In addition, a previous study in mice found that ashwagandha may affect serotonergic transmission. The goal of this randomized, double-blind, placebo-controlled trial was to test the efficacy of ashwagandha root extract as an adjunct therapy for OCD.

Ashwagandha roots were collected in Saravan, Iran, in August 2013. The extract was prepared at the industrial pharmacy lab at the School of Pharmacy at Mashhad University of Medical Sciences in Mashhad, Iran. The roots were dried and powdered, then percolated with 70% ethanol. The resulting extract was evaporated under pressure and freeze-dried to yield a fine powder. The researchers filled 250-mg capsules with either a mixture of 30 mg of the powdered extract and lactose (an excipient) for the treatment group or lactose only for the placebo group.

The study was conducted between March 2015 and September 2015 at the Mashhad University of Medical Sciences. Thirty patients met the following inclusion criteria and were enrolled in the study: diagnosis of OCD per the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision and current treatment with SSRIs. Patients were randomly assigned to the treatment group (n = 15; one male and 14 females) or the placebo group (n = 15; two males and 13 females). To avoid potential adverse gastrointestinal effects, the patients in the treatment group were instructed to take one capsule daily and increase the dosage by one capsule every four days until they were taking four capsules daily (adding up to 120 mg of extract). At the end of six weeks, the treatment was decreased in the same manner.

The severity of OCD symptoms was assessed in all patients using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) symptom checklist, a 10-question scale with scores ranging from 0 (no symptoms) to 40 (extreme symptoms). Each patient completed the Y-BOCS checklist at baseline and after six weeks of study intervention.

From baseline to the end of the study (six weeks), the median Y-BOCS score decreased from 26 to 14 in the treatment group and from 18 to 16 in the placebo group, a significant between-group difference (P < 0.001). At baseline, seven patients in the treatment group and five in the placebo group suffered from comorbid anxiety disorders (i.e., they had one or more anxiety disorders in addition to OCD). The patients in each group were divided into those with comorbid anxiety disorders and those without, and the average reduction of Y-BOCS scores for these subgroups was compared. In both groups, the average reduction of Y-BOCS scores in patients with comorbid anxiety disorders was not significantly different from patients without anxiety disorders. No adverse effects were reported in either group during the study.

According to the authors, this study is the first attempt to investigate the effects of ashwagandha root extract in patients with OCD. Based on the results of this study, the authors concluded that “W. somnifera extract may be beneficial as a safe and effective adjunct to SSRIs in the treatment of OCD.”

Acknowledged limitations include the study’s small sample size, short duration, and lack of a phytochemical analysis of the extract, which could have helped identify the active constituents associated with the observed beneficial effects. In addition, due to the study design, the researchers were unable to determine if the observed anti-obsessive effects were dose-dependent. Unfortunately, there was also a large difference in baseline symptom severity (per the Y-BOCS scores) and the number of patients taking clomipramine or valproate sodium between the treatment and placebo groups. For these reasons, the results of this study should be interpreted with caution.

–Shari Henson