Treatment of Mild Cognitive Impairment With Transcutaneous Vagal Nerve Stimulation (TVNS MCI)

Patients with amnestic mild cognitive impairment (MCI) often have compromised quality of life (QOL). Cognitive impairment is a major contributor to decrements in QOL and progression of MCI often leads to loss of independence and withdrawal from social participation. MCI, in many patients, is an early expression of neurodegenerative disease. Patients with MCI frequently convert to Alzheimer's disease (AD) (12-16 percent by some estimates per year). Treatments for MCI are of limited scope and availability and of limited effectiveness. Thus, there is great need for treatments that can improve cognition and extend QOL in patients with MCI. The investigators propose to investigate the effect of a non-invasive and safe intervention that should have direct influence on brain systems underlying AD, transcutaneous vagal nerve stimulation (tVNS).

Patients with amnestic mild cognitive impairment (MCI) often have compromised quality of life (QOL). Cognitive impairment is a major contributor to decrements in QOL and progression of MCI often leads to loss of independence and withdrawal from social participation. MCI, in many patients, is an early expression of neurodegenerative disease. Patients with MCI frequently convert to Alzheimer's disease (AD) (12-16 percent by some estimates per year). Treatments for MCI are of limited scope and availability and of limited effectiveness. Thus, there is great need for treatments that can improve cognition and extend QOL in patients with MCI. The investigators propose to investigate the effect of a non-invasive and safe intervention that should have direct influence on brain systems underlying AD, transcutaneous vagal nerve stimulation (tVNS). Transcutaneous vagal nerve stimulation (tVNS) may ameliorate symptoms of MCI. The investigators have demonstrated, in patients with epilepsy, that VNS improves memory; however, tVNS has not been used to treat patients with MCI. tVNS can now be performed without surgery by transcutaneous stimulation of the auricular branch with electrodes on the external ear. tVNS has the potential to improve cognition and may even alter the course of decline in patients with MCI. The investigators will employ a multimodal MRI-based neuroimaging approach combined with comprehensive and targeted cognitive testing to assess changes with tVNS in cognition in patients with MCI. The investigators will evaluate the effects of tVNS on patients who have been diagnosed with MCI as well as healthy older controls. Very little in the way of mechanistic data or understanding of individual differences in response to tVNS in MCI/AD has been published. Thus, this is a necessary study to evaluate the potential utility of tVNS to enhance cognitive performance in patients with MCI. These data may serve as a platform for supporting the development of a clinical treatment trial with this technology.

All participants will be assigned to either transcutaneous vagal nerve stimulation or sham for the first session, then switch to the other condition for their second session after a 1 week washout period.

The sham stimulation experience is very similar to the tVNS stimulation experience. The electrodes are placed in a proximal location. Thus, without knowledge of the anatomy, the participants will be unable to determine which stimulation session is the tVNS one.

This group will receive transcutaneous vagal nerve stimulation, initially. Participants will be randomized between the two arms of the crossover sessions (initial tVNS vs. initial Sham). Behavioral portions of the testing will then be carried out twice, with at least 72 hours between sessions (to avoid carryover effects).

This group will receive sham stimulation, initially. Participants will be randomized between the two arms of the crossover sessions (initial tVNS vs. initial Sham). Behavioral portions of the testing will then be carried out twice, with at least 72 hours between sessions (to avoid carryover effects).

Non-invasive stimulation provided by transcutaneous electrical nerve stimulation device at 20Hz, 100 μs pulse width

The Rey Auditory Verbal Learning Test (RAVLT) is a verbal learning and memory task with a 15-item word list learned over 5 trials. The total delayed recall score is the number of total correct words recalled (ranging from 0 to 15) after a 30 minute delay.

30 minutes after administration of 5 list learning trials; 2 minutes to complete delayed recall of word-list

Inclusion Criteria: Diagnosed with amnestic mild cognitive impairment/mild Alzheimer's disease Preservation of independence in functional abilities Healthy aged adults without MCI to serve as control group Exclusion Criteria: Other medical or neurological conditions that may be associated with significant impaired cognition (e..g, moderate to severe traumatic brain injury, epilepsy, etc...) Vascular dementia or other non-AD spectrum diagnosed neurodegenerative disorders Significant current depression Uncorrected vision/hearing loss Unable to undergo MRI exam