BDNF and depressive disorder: The novel data, regarding relation of BDNF to microbiota must be further explored, since decreased levels of BDNF are associated with the pathogenesis of several major diseases including depression and Alzheimer's disease (35, 36, 38, 39), while daily consumption of meals favoring Faecalibacterium prausnitzii and/or Prevotella might possibly prevent or slow neurodegenerative processes, including dementia.