The gut microbiome plays an integral part in neurodegeneration through its direct interaction with the autonomic nervous system (ANS) via the vagal nerve. The aim of this pilot study is to investigate changes in ANS function in patients with mild Alzheimer’s Disease (AD) following administration of probiotics, compared to placebo (no active probiotics). Patients with mild AD (MMSE: 19-23) who fulfil all eligibility criteria were enrolled on the study and randomly assigned to take probiotics or placebo (control) for 16 weeks. We collected various data at baseline and study completion (weeks 0 & 16), including electrocardiogram (ECG) during resting state (eyes open / closed). We analyse the ECG data of 10 patients (Nstudy=5) who have completed the study and compare their ANS function at baseline and study completion via Poincaré plot measures SD1, which represents heart rate short-term variability influenced by parasympathetic modulation, and SD2, representing long-term variability influenced by sympathetic activation. The analysis shows mean increase in ANS function (SD1 and SD2) at the end of the study week in both groups, with the probiotic group displaying a higher increase (figure 1). None of the changes were statistically significant (within-subjects: paired t-test; between subjects: independent t-test, unequal variances; α=0.05), but this is expected given the small sample size per group. Our preliminary findings are encouraging for further investigation of the ANS function, and future work will correlate ANS function with cognitive function scores, inflammatory markers and gut microbiome composition.