A randomized clinical trial examining the impact of LGG probiotic supplementation on psychological status in middle-aged and older adults

Abstract Cognitive decline is common in older adults and more than 5 million Americans suffer from Alzheimer's disease (AD). A number of physiological processes including systemic inflammation, excess adiposity, and impaired glucoregulation arise from a combination of genetic and behavioral factors and increase risk for developing AD or other forms of dementia. Recent research suggests that the gut microbiome may moderate these pathological processes and possibly influence cognitive outcomes. This paper reviews the methodology for a double-blind, randomized clinical trial examining the influence of Lactobacillus GG (LGG) probiotic supplementation on mood and cognitive functioning in middle-aged and older adults. Our two primary hypotheses include: 1) Participants randomized to the probiotic group will show greater improvements in psychological status compared to participants in the placebo group; 2) Participants randomized to the probiotic group will show greater improvements in executive functioning and processing speed, as evidenced through performance on neuropsychological testing, than participants in the placebo group. We anticipate these results will inform future efforts on the feasibility of LGG probiotic supplementation as an intervention for psychological status and cognitive functioning and further elucidate the link between the gut microbiome and cognitive health.