Effects of probiotics on cognitive and emotional functions in healthy older adults: Protocol for a double-blind randomized placebo-controlled crossover trial.

Aging is a process that includes changes in cognitive and emotional functions, as well as changes in the diversity and integrity of gut microbiota. Probiotic treatments have recently been studied as a potential new therapeutic approach to alleviate a wide range of problems in other populations; however, clinical studies in older adults remain insufficient and limited. Thus, the aim of this project is to evaluate the efficacy of a multispecies probiotic formulation as a therapeutic strategy for attenuating the emotional and cognitive decline associated with aging in adults over the age of 55. This is a double-blind randomized placebo-controlled crossover trial involving at least 32 older adults and comparing two conditions: (a) probiotic, providing a multispecies probiotic for 10 weeks (Lactobacillus rhamnosus and Bifidobacterium lactis); and (b) placebo, receiving a harmless substance (potato starch). Despite the increasing use of probiotics for the treatment of cognitive and emotional problems, no study has yet focused on this group, to the best of our knowledge. Therapeutic strategies of the kind outlined in this protocol will help to shed light on the current state of knowledge about this topic, as well as promote health programs tailored to this population, which would encourage active aging and healthy lifestyles. Not only do we expect improvements in the emotional dimension in terms of anxiety, stress, depression, and sleep quality, we also expect improvements in the cognitive dimension in terms of attention, memory, and decreased impulsivity.