Abstract
Population ageing is a phenomenon that represents a major societal challenge affecting medical, social, and economic areas. Higher age is accompanied by a higher susceptibility to neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD), which are at the forefront of scientific research but still cannot be successfully treated.
The bi-directional microbiota-gut-brain axis is a term that resonates not only in the scientific world but also throughout society. It is considered to be key in modulating gut-brain function. Imbalances in the gut microbiota have been linked to the development and symptomatology of a number of diseases. Studies suggest a link between disruption of the gut microbiota and a wide range of diseases. Impaired mood, memory, AD or PD, but also with disruption of natural healthy ageing. The cause is likely to be increased permeability of the intestinal and blood-brain barrier induced by disruption of the gut microbiota (1,2). An imbalance in the gut microbiota can induce inflammation, which is associated with the pathophysiology of many diseases including obesity, type 2 diabetes mellitus and AD [3]. In addition, bacteria produce large amounts of amyloids and lipopolysaccharides contributing to the modulation of signalling pathways and the production of pro-inflammatory cytokines (IL-8, IL-6 and TNF-alpha) associated with AD pathogenesis. Probiotics, especially a subgroup called psychobiotics, are one of the options to effectively alter the composition of the gut microbiota (4,5).