Vagus Nerve Stimulation to Enhance Memory in Aging
Trial Snapshot
- Phase
- Not Applicable
- Status
- Not yet recruiting
- Sponsor
- Stanford University
- Enrollment
- 150
- Locations
- 1
- Primary Endpoint
- Change in Recognition Memory (d-prime)
Study Overview
Brief Summary
The aim of this study is to determine whether non-invasive vagus nerve stimulation enhances memory formation in cognitively healthy older adults and whether the effects of stimulation depend on gut and brain health.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Crossover
- Primary Purpose
- Basic Science
- Masking
- Single (Participant)
Masking Description
Because the active electrode will be placed on the cymba conchae and the sham on the earlobe, full double-blinding is not feasible; as such, the experimenter will be aware of the active/sham condition status of each experimental block. Participants will be masked/blinded to condition order and hypotheses (they will not be informed which blocks are active vs. sham).
Eligibility Criteria
- Ages
- 18 Years to 80 Years (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Ages 18-30 years or 65-80 years
- •Normal or corrected-to-normal vision (visual acuity)
- •Fluent in English
Exclusion Criteria
- •Symptoms of memory loss
- •History of a neurological, psychiatric, or medical condition that could affect cognition or preclude MRI or pupillometry
- •Use of medications known to alter cognition
- •For older adults, neuropsychological performance that falls outside 1.5 standard deviations of age-adjusted norms and no self-reported memory or attention complaints
Arms & Interventions
Active vagus nerve stimulation
Participants will receive active stimulation during memory encoding of picture-word pairs. Active stimulation will occur during two learning phases of the learning and memory task. The total duration of these two phases will be less than 30 minutes.
Intervention: Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) (Device)
Sham stimulation
Participants will receive sham stimulation during memory encoding of picture-word pairs. Sham stimulation will occur during two learning phases of the learning and memory task. The total duration of these two phases will be less than 30 minutes.
Intervention: Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) (Device)
Outcomes
Primary Outcomes
Change in Recognition Memory (d-prime)
Time Frame: post-active vs post-sham stimulation; up to 2 hours of task
d' is a signal-detection sensitivity index-how well participants discriminate old (studied) from new (unstudied) items, independent of response bias. Computed as d' = Z(hit rate) - Z(false-alarm rate) from the old/new recognition memory test. Primary analysis is within-person Δhigh-confidence d' (based on "sure old" responses in the 4-point "sure old", "unsure old", "unsure new", "sure new" scale, Δ = active - sham) and Δoverall d' (based on "sure old" and "unsure old" responses). Main comparison is older vs. young, and within the older group also testing moderation by gut-brain axis measures and interactions with preclinical Alzheimer's disease pathology (pTau217, pTau181, Aβ42:40).
Secondary Outcomes
No secondary outcomes reported
Investigators
Anthony David Wagner
Professor, Department of Psychology
Stanford University