Effects of probiotic supplements on cognition, anxiety, and physical activity in subjects with mild and moderate Alzheimer's disease: A randomized, double-blind, and placebo-controlled study

Probiotics have been suggested as an effective adjuvant treatment for Alzheimer's disease (AD) due to their modulating effect on the gut microbiota, which may affect the gut-brain axis. Therefore, we aimed to evaluate the effects of two different single-strain probiotics on cognition, physical activity, and anxiety in subjects with mild and moderate AD. Eligible patients (n = 90) with AD were randomly assigned to either of two interventions [Lactobacillus rhamnosus HA-114 (10¹⁵ CFU) or Bifidobacterium longum R0175 (10¹⁵ CFU)] or placebo group, receiving probiotic supplement twice daily for 12 weeks. The primary outcome of the study was cognitive function measured by using the two tests, namely, the Mini-Mental State Examination (MMSE) and the categorical verbal fluency test (CFT). Secondary outcomes included a performance in Activities of Daily Living (ADL), the Lawton Instrumental Activities of Daily Living (IADL) scale, and the Generalized Anxiety Disorder (GAD-7) scale. Linear mixed-effect models were used to investigate the independent effects of probiotics on clinical outcomes. After 12 weeks, MMSE significantly improved cognition (P _Interaction < 0.0001), with post hoc comparisons identifying significantly more improvement in the B. longum intervention group (differences: 4.86, 95% CI: 3.91-5.81; P < 0.0001) compared with both the placebo and L. rhamnosus intervention groups (differences: 4.06, 95% CI: 3.11-5.01; P < 0.0001). There was no significant difference between the two intervention groups (differences: -0.8, 95% CI: -1.74 to 0.14; P = 0.09). In conclusion, this trial demonstrated that 12-week probiotic supplementation compared with placebo had beneficial effects on the cognition status of patients with AD.