Efficacy of a multispecies probiotic as adjunctive therapy in generalized anxiety disorder: a double blind, randomized, placebo-controlled trial

ABSTRACT

Objectives: Studies have shown that probiotics may decrease anxiety symptoms, but to our knowledge so far no trial has investigated the effects of probiotics in generalized anxiety disorder (GAD). The aim of the present study was to determine the effects of probiotics as adjunctive therapy on anxiety severity and quality of life (QOL) in patients with GAD.

Methods: Forty-eight drug-free patients with a diagnosis of GAD based on DSM-V criteria were randomly assigned to two groups to receive daily either one capsule of probiotics or placebo in addition to 25 mg sertraline for 8 weeks. Probiotic capsules contained 18*10⁹ CFU Bifidobacterium longom, Bifidobacterium bifidum, Bifidobacterium lactis and Lactobacillus acidophilus bacteria.

Results: Intention to treat analysis was performed in 39 Patients who completed at least 4 weeks of the intervention. After 8 weeks, the score of Hamilton Rating Scale for anxiety (HAM-A) decreased more in the probiotics + sertraline (PS) group (p = 0.003). Although the reduction of Beck Anxiety Inventory (BAI) was also more in the PS group, it was not significantly different from that of the sertraline alone(S) group. Moreover, despite the greater reduction of State-Anxiety Inventory score in the PS group, the score of Trait-Anxiety Inventory was not statistically different between the two groups at week 8. With regard to QOL, there was no significant difference between the two groups in the change of the score of QOL domains.

Conclusions: Probiotics + sertraline combination was superior to sertraline alone in decreasing anxiety symptoms after 8 weeks in patients with GAD, although it did not affect QOL.

KEYWORDS:

• Generalized anxiety disorder
• probiotic
• sertraline
• quality of life
• anxiety

Acknowledgements

The authors thank Takgene Zist Company for their support in providing probiotic supplements. Thanks are also extended to study participants, as well as the staff of Ziaeean hospital and laboratory for their cooperation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Sevda Eskandarzadeh is M.Sc in nutrition sciences at Iran University of Medical Sciences and bachelor in the same major at Shahid Beheshti University of Medical Sciences.

Mohammad Effatpanah is a subspecialist in child & adolescent psychiatry and faculty member at Tehran University of Medical sciences.

Kianoush Khosravi-Darani is a full professor of Food Biotechnology at the research department of Food Technology in Shahid Beheshti University of Medical Sciences.

Reza Askari is psychiatrist at Ziaeian hospital, Tehran University of Medical Sciences.

Agha Fatemeh Hosseini is M.Sc. in Biostatistics, Faculty member at Department of Biostatistics, School of Public Health, Iran University of Medical Sciences.

Mahnaz Reisian is M.Sc. in nutrition sciences at Iran University of Medical Sciences and bachelor in public Health at Babol University of Medical Sciences.

Shima Jazayeri, M.D., Ph.D. in nutrition. Now she is working as associate professor in Iran University of Medical Sciences.

Additional information

Funding

This work was supported by the Vice Chancellor for Research, Iran University of Medical Sciences [research no. 95-03-27-29541].