Psychobiotic properties of probiotic lactic acid bacteria and bifidobacteria in paediatric neurological disorders

Recent studies have highlighted a close relationship between intestinal dysbiosis and paediatric neurological disorders, such as autism spectrum disorders (ASD), attention deficit hyperactivity disorder (ADHD), epilepsy, cerebral palsy (CP). In the last decades, the relevance of a strong connection between the intestinal microbiota and the brain, i.e., the gut-brain axis, has been broadly ascertained. Through this association, gut microbes contribute to shape development, physiology, and cognitive functions of the brain. The bidirectional communication between gut microbiota and brain involves a complex set of molecular signals that influence synaptic plasticity, learning, memory, mood, and the brain's excitatory-inhibitory balance. Microbial metabolites play a fundamental role in modulating brain activity. Emerging scientific evidence suggests that neurological and psychiatric conditions, including ASD, ADHD, anxiety, and depression, may not simply stem from brain malfunctions, but rather from imbalances in the gut microbiota, which contribute to disrupt brain function and development. In this context, psychobiotics, i.e., a specific group of probiotic microorganisms, have garnered interest for their potential to modulate brain functions. Several pre-clinical studies on psychobiotics have shown promising results in managing paediatric neurological disorders, including ASD and ADHD. However, there is only a limited number of clinical studies to support the use of psychobiotics as therapeutics. This review summarizes and discusses the link between gut microbiota and neurological disorders in children, and the current status of studies investigating the potential application of psychobiotic lactic acid bacteria (LAB) and bifidobacteria for treating these paediatric disorders.