Rare Gut Bacteria Linked to Restless Legs Syndrome

One common sleep disorder in which the microbiome may play a role is restless legs syndrome (RLS). While the pathogenesis of RLS is not fully understood, a relative state of brain iron deficiency has been described in patients with RLS and appears to induce changes in several pathways known to be involved in the disease.

RLS is a sensorimotor disorder characterized by a complaint of a strong, nearly irresistible urge to move the limbs that is often accompanied by other uncomfortable sensations. These symptoms begin or worsen during periods of rest or inactivity such as lying down or sitting, are partially or totally relieved by movement such as walking or stretching, and occur exclusively or predominantly in the evening or at night. Small intestine bacterial overgrowth (SIBO) is a condition in which rare gut-residing bacteria are over-represented in the gut.

Scientists at the Stanford Sleep Center (Redwood City, CA, USA) recruited at the center three groups: RLS and low peripheral iron stores of less than 50ng/mL and/or transferrin saturation of less than 18%, RLS and normal peripheral iron stores, and insomnia (control).

Participants completed questionnaires concerning sleep and SIBO symptoms and were sent home with the Fecal Swab Collection and Preservation System fecal collection kit (Norgen Biotek, Thorold, ON, Canada; https://norgenbiotek.com) and a SIBO Home Breath Test Kit, (Mullumbimby, Australia).

Fecal samples are assayed by the University of Minnesota Genomics Center (Minneapolis, MN, USA) with microbial community profiling evaluated by 16S ribosomal RNA (16S rRNA) gene sequencing protocols. SIBO breath samples are evaluated by Aerodiagnostics (Concord, MA, USA) for hydrogen and methane abnormalities.

The investigators reported that seven participants diagnosed with RLS (three men and four women) have thus far completed the protocol. All indicated poor sleep quality (Pittsburgh Sleep Quality Index [PSQI] ≥ 5) and moderate to severe symptoms of RLS (IRLS scores ranging from 13 to 34/40). SIBO was present in all seven participants (100%) whereas general population rates are estimated to be 6% to15%.

Daniel Jin Blum, PhD, DBSM, an adjunct clinical instructor and first author of the study, said, “We've observed extremely high rates of small intestinal bacterial overgrowth in the RLS group. Exploring the relationship between RLS and gut microbial health has the potential to open novel avenues for possible detection, prevention and treatment for RLS and other sleep disorders.” The study was presented on June 9, 2019, at the Annual meeting of the Associated Professional Sleep Societies held in San Antonio, TX, USA.

Related Links:
Stanford Sleep Center
Norgen Biotek
SIBO
University of Minnesota Genomics Center
Aerodiagnostics