Transcutaneous Vagus Nerve Stimulation for Attention and Memory

Attention and memory problems are common in veterans with traumatic brain injuries (TBI), particularly when accompanied by depression and/or posttraumatic stress disorder (PTSD). Current treatments for these issues often have limited effectiveness or unwanted side effects. Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive technique that uses gentle electrical impulses delivered through electrodes placed on the ear. This stimulation targets the vagus nerve, which plays a key role in regulating brain areas involved in attention and memory. By enhancing the activity of these brain regions, taVNS shows potential as a novel treatment option for improving cognitive functions like attention and memory. In this study, researchers aim to determine whether taVNS can enhance attention and memory in veterans with TBI. Participants will complete a single study visit lasting 2.5 to 3 hours. The visit includes two taVNS sessions, one active and one sham (placebo), to compare their effects. Sham stimulation mimics the sensation of taVNS but does not deliver electrical current to the vagus nerve. This design allows researchers to isolate the specific effects of taVNS. Procedures: 1. Screening (40 minutes): Participants will begin by completing questionnaires about their medical history, memory concerns, alcohol and substance use, mood, and demographics. Vital signs (heart rate, blood pressure, and temperature) will also be measured to confirm eligibility. 2. Session 1 (approximately 40 minutes): Participants will complete a computer-based attention task that involves responding to specific visual cues on a screen. This task takes about 10 minutes. taVNS will then be delivered using electrodes placed on the left ear. For this session, participants will either receive active stimulation or sham stimulation, randomly assigned. The stimulation lasts 20 minutes. After the stimulation, participants will repeat the attention task to assess changes in performance. 3. Break: Participants will have a short break between sessions, during which they can rest or engage in light activities. 4. Session 2 (approximately 40 minutes): The same sequence of procedures will be repeated, but participants will receive the alternate type of stimulation (active or sham) in this session. The order of active and sham stimulation is randomly assigned, and participants will not know which session is delivered first. Throughout both sessions, participants' heart rate variability (HRV) will be monitored using a lightweight chest device. HRV provides insights into how the body responds to stimulation and helps evaluate taVNS's physiological effects.