MAPT and early-onset autosomal dominant Alzheimer disease: • Improvement or no decline from baseline on the ADAS-cog score in 33% and on the MMSE in 64% of participants.• Significant improvement from baseline was sustained at 6 months for the ADAS (median improvement of 3 points, p = 0.011, n = 16) and MMSE (median improvement of 2 points, p = 0.012, n = 16).• After 12 months of VNS, the median change in CSF-tau was a reduction of 7.7% (p = 0.003, n = 15)• Conclusion: a positive effect of VNS on cognition in Alzheimer's disease after one year of treatment