Psychobiotics: An Emerging Concept in Mental Health Care

Benefits reported for depressed mood, anxiety, ADHD, autism and dementia.

Posted Sep 04, 2019

Psychobiotics are a recently characterized class of probiotics that affect brain function via immune, neural, and metabolic pathways. Recent research findings suggest that certain psychobiotics may ameliorate symptoms of anxiety, depressed mood and autistic spectrum disorder, and may improve cognitive function in individuals with neurodegenerative diseases such as Alzheimer’s disorder and Parkinson’s disease. This post is offered as a concise review of essential concepts and recent research findings in the broad area of psychobiotics. (Readers can find a more in-depth discussion in Cheng et al 2019.)

The role of microorganisms in the gut-brain axis

The human gut contains trillions of microorganisms, a number far greater than the total number of cells in the body. Specific microorganisms that populate each person’s gut are determined by a variety of factors including diet, gender, age, and genetics. Accumulating research findings from animal and human studies have established that gut microorganisms play important roles in regulating immune function, maintaining healthy energy balance and modulating the nervous system. Complex pathways in the ‘gut-brain’ axis result in the co-occurrence of gastrointestinal disorders and disorders of the central nervous system when the microbiome is out of balance. Imbalances in or abnormally low populations of specific gut microorganisms have been found in individuals with major depressive disorder, ADHD, Alzheimer’s disease, Parkinson’s disease, and autism.

The beneficial effects of psychobiotics on mood and anxiety are probably mediated by different mechanisms of action including increased synthesis of serotonin and other neurotransmitters, brain-derived neurotrophic factor (BDNF), and general anti-inflammatory effects. Findings of animal and human studies suggest that specific strains of Lactobacillus may increase CNS levels of serotonin, norepinephrine and dopamine and increase synthesis of BDNF resulting in improved memory and global cognitive function, and reduction in symptoms of anxiety and depressed mood.

Promising but preliminary findings in Alzheimer’s disease

Investigations of psychobiotics using animal models of Alzheimer's disease (AD) have reported improvements in learning and memory, and reductions in the number of amyloid plaques, and reduced markers of inflammation. To date, few human studies have been done on psychobiotics in AD and findings are mixed. Some findings support that certain probiotics may improve memory in individuals with mild early AD, but individuals with severe AD probably do not benefit from probiotic supplementation.

Bottom line

Supplementation with select microorganisms that influence the gut-brain axis may be beneficial for a variety of mental health problems including depressed mood, anxiety, and autism, and may reduce the severity of cognitive symptoms in individuals with neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. Large prospective placebo-controlled human studies are needed to further investigate potential benefits of specific psychobiotics in mental health care broadly, and to determine optimal combinations and dosages of specific microorganisms when used to treat different psychiatric and neurodegenerative disorders. 


Cheng, L., Liu, Y., Wu, C, et al (2019) Psychobiotics in mental health, neurodegenerative and neurodevelopmental disorders. J. Food Drug Anal. 27 (3): 632-648.