Plain language summary
On the Alzheimer’s disease spectrum, which is the most common cause of dementia, the typical symptom at onset is impaired memory. As the disease progresses, other cognitive domains, such as language, visuospatial cognition, and executive function, are impaired, gradually making it impossible to maintain independence in daily life. The aim of this study was to test the protective effects of 12 weeks of supplementation with heat-treated Lactiplantibacillus OLL2712 cells on memory function in older adults. This study was a double-blind placebo-controlled trial in which participants were randomly assigned to the active or placebo group. Results showed that OLL2712 consumption had a protective effect on memory function in older adults. However, there was no significant effect of OLL2712 intake on verbal memory in either of the analyses. Furthermore, in the gut microbiota analysis, the bacterial composition of the active group showed significantly lower abundance ratios of bacterial species linked to inflammation (Lachnoclostridium, Monoglobus, and Oscillibacter). Authors conclude that continuous intake of OLL2712 may be an effective approach to protect memory function in older adults.
The use of probiotics is expected to be an intervention in neurodegenerative conditions that cause dementia owing to their ability to modulate neuroinflammatory responses via the microbiome-gut-brain axis. Therefore, we selected Lactiplantibacillus plantarum OLL2712 (OLL2712), the optimal anti-inflammatory lactic acid bacteria strain with high IL-10-inducing activity in immune cells, and aimed to verify its protective effects on memory function in older adults. A 12-week, randomized, double-blind, placebo-controlled trial was performed with older adults over the age of 65 years with declining memory. The participants consumed either powder containing heat-treated OLL2712 cells or placebo. Memory function was assessed using a computer-assisted cognitive test, Cognitrax. Daily dietary nutrient intake was assessed using the Brief-type Self-administered Diet History Questionnaire (BDHQ). The composition of the gut microbiota was analyzed by fecal DNA extraction and 16S rDNA sequencing. Data from 78 participants who completed the entire procedure were analyzed, and significant improvements in composite memory and visual memory scores were observed in the active group, after accounting for the effect of daily nutritional intake (p = 0.044 and p = 0.021, respectively). In addition, the active group had a lower abundance ratio of Lachnoclostridium, Monoglobus, and Oscillibacter genera, which have been reported to be involved in inflammation. The present study suggests that OLL2712 ingestion has protective effects against memory function decline in older adults.