An Update on the Relationship Between the Gut Microbiome and Obsessive- Compulsive Disorder

The gut microbiome, the collection of microbes and their genetic material in the human gastrointestinal tract, has recently become a topic of interest in psychiatry. To date, animal studies have repeatedly shown behavior to be affected by alterations in the gut microbiota. Furthermore, studies in clinical psychiatric populations have also illustrated that microbial dysbiosis may play a role in these conditions, but results have been inconsistent. Given the existing animal and human literature providing evidence for a role of the microbiome in anxiety and depressive disorders, this review explores and develops similar lines of evidence in obsessive-compulsive disorder. Theoretical treatment options targeting the gut microbiome are also discussed. [Psychiatr Ann. 2017;47(11):542-551.] Obsessive-compulsive disorder (OCD) is a psychiatric condition marked by recurrent intrusive thoughts and ritualistic behaviors aimed at reducing the associated distress. The etiology of OCD is complex and involves multiple pathways, with imbalances in central serotonin, glutamate, and dopamine systems thought to play a causative role. This etiological basis remains largely theoretical and has received mixed scientific support. The current theories are premised on the observed benefit of pharmacological interventions such as serotonin reuptake inhibitors (SRIs). Given that 40% to 60% of patients with OCD do not respond to first-line treatments such as SRIs or cognitive-behavioral therapy (CBT),1 it is important that Jasmine Turna, BSc, PhD(C), is a Research Assistant, MacAnxiety Research Centre, McMaster University; and a Graduate Student, MiNDS Neuroscience Graduate Program, McMaster University. Beth Patterson, BScN, MSc, is a Research Nurse, Department of Psychiatry and Behavioural Neurosciences, McMaster University; and a Research Research Manager, MacAnxiety Research Centre, McMaster University. Michael Van Ameringen, MD, FRCPC, is a Professor, Department of Psychiatry and Behavioural Neurosciences, McMaster University; the Director, MacAnxiety Research Centre, McMaster University; and a Psychiatrist, Hamilton Health Sciences. Address correspondence to Jasmine Turna, BSc, PhD(C), MacAnxiety Research Centre, McMaster University, 1057 Main Street W, L02, Hamilton, ON, L8S 1B7; email: [email protected]. Grant: M. V. A. has received grants from the Hamilton Academic Health Sciences Organization and the Canadian Foundation for Innovation. Disclosure: Beth Patterson reports that her spouse is on the speakers bureau for Lundbeck, Purdue, and Allergen; her spouse is a consultant for Purdue and Allergen; and her spouse has performed contracted research for Shire, Janssen-Ortho, and Pfizer. Michael Van Ameringen is on the speakers bureau for Lundbeck, Purdue, and Allergen; is a consultant for Purdue and Allergen; and has performed contracted research for Shire, Janssen-Ortho, and Pfizer. The remaining author reports no relevant financial relationships. doi: 10.3928/00485713-20171013-01 © S hu tte rs to ck