The need is acute for more safe and effective ways to help patients live more comfortably with chronic neurological conditions like Parkinson’s disease (PD) and Autism Spectrum Disorder (ASD). Despite receiving modern evidence-based medical treatment, many patients experience frequently distressing symptoms.
Recent clinical research in PD and ASD patients suggests certain probiotic strains, known as psychobiotics, can attenuate neurological symptoms. While probiotics like those found on grocery store shelves and dairy cases are typically associated with improving digestion, psychobiotics exert an influence on the brain via the gut-brain axis. They offer a novel and low-risk option for PD and ASD patients to explore in conjunction with more traditional therapies.
How can the gut microbiota communicate with the brain?
Knowledge of the gut-brain axis (GBA) has grown exponentially in recent years, from relatively little information a decade ago, to more than 1200 scientific papers published on the topic in 2021 alone. The GBA includes all of the pathways that connect the central nervous system (CNS) and the gastrointestinal (GI) tract: the vagus nerve as well as bloodborne immune factors, hormones such as dopamine and serotonin, and microbial metabolites.
This GBA connection allows the brain and gut to influence one another in surprisingly intimate ways. The gut microbiota – all the microorganisms living in the gut, including bacteria, fungi, yeasts and viruses – influences brain development and function, including cognition and mental health. Meanwhile, the CNS affects the composition and function of gut microbiota not only by controlling gut motility and permeability, but also via hormone levels that can directly influence microbial gene expression.
The existence of the GBA provides an explanation for the high incidence of GI symptoms in neurological disease patients and vice versa. It also provides a potential way to directly influence neurological symptoms by introducing specific probiotic strains into the gut microbiota.
Taking advantage of the GBA to help PD and ASD patients
Psychobiotics are probiotic strains that are neurologically active. Animal studies show that oral administration of psychobiotics can help regulate neurotransmitters and gut-produced hormones, changing their levels in the bloodstream and brain tissue via the GBA. Such molecules play vital roles in controlling mood, movement, learning, memory processes, and cognitive function.
Certain psychobiotic strains like Lactobacillus plantarum PS128 (PS128) modulate serotonin and dopamine levels in animals, and abnormal levels of these hormones are seen in PD and ASD. This immediately raises the question of whether psychobiotics might show a benefit in these patients.
Initial clinical results are promising. A recent pilot study in patients with PD found that Lactobacillus plantarum PS128, alongside conventional treatment, improved motor function and quality of life. In children and adolescents with ASD, multiple published and ongoing trials show that PS128 can significantly improve anxiety levels, shared attention, and communication skills. Interestingly, benefits have been observed regardless of whether the children had GI symptoms, suggesting PS128 can positively affect the gut-brain axis directly.
The future of psychobiotics and neurological illness
The use of psychobiotics by people with neurological illnesses like PD and ASD is potentially attractive from several angles. First, the illnesses themselves often present with significant GI tract symptoms. In the case of PD there are also suggestions that IBD or gut dysbiosis may play a role in disease onset for some patients. This highlights the connection between the CNS and the gut, a connection that psychobiotics are uniquely poised to exploit. Other neurological conditions like anxiety, depression, headache, and sleep difficulties are also commonly found among those with GI diseases (refr).
In addition, specific psychobiotics such as Lactobacillus plantarum PS128 are known to regulate levels of the hormones dopamine and serotonin, hormones which are depleted in PD and ASD patients, respectively. Other psychobiotics may affect the CNS in ways that make them useful for addressing a different spectrum of mind, mood and/or movement symptoms. Lastly, probiotics are well recognized for being safe for long-term use with few or no reported side-effects, unlike many drugs for chronic conditions such as PD and ASD.
Neurologically active probiotics offer an exciting pathway for research in the field of mental health. We look forward to the future research that will be required to gauge their mechanism and efficacy for multiple psychiatric disorders.
David Lee is the COO of Bened Life. He is on a mission to elevate the profile of live, gut-brain therapeutics in an untapped market. He holds a BS in Molecular Biology from UC San Diego and has held positions in lab research, biotech research, and bio business research that focused on his personal interest in translational biology. With over 16 years in the science and probiotic industry, Lee has led a team making strides in research and development, education, and production of gut-brain axis supplements.