The intervention will be studied in 140 older individuals using a randomized cross-over design of sham versus RAVANS stimulation (2 sessions separated by 4 weeks) during a functional magnetic resonance imaging (fMRI) task. Participants will then be randomized to daily tVNS or sham sessions during 10 visits within two weeks, and two follow-up cognitive assessments each after 2 months of the last intervention session. The face-name association task will be the main outcome measure. The investigators will also draw blood twice to examine whether the response on the outcome is dependent on Alzheimer's disease related biomarker, and whether RAVANS has effects on inflammatory responses.
In this research study the investigators want to find out if a non-invasive electrical brain stimulation method called RAVANS (also called tVNS) can have a beneficial effect on cognition in older individuals. The investigators also want to understand whether certain individual factors contribute to the effect of RAVANS on cognition. RAVANS is only used in research studies.