Ten study visits will be completed by each participant. The initial visit will include a blood draw and a baseline memory evaluation. Afterwards, participants will be randomized to begin with one of 3 conditions of HD-tDCS. The three conditions are sham-control, active stimulation to left frontal region, and active stimulation to left temporal region. All participants will be expected to completed each HD-tDCS condition, which will be counterbalanced and separated by 14 days. Active HD-tDCS will be applied at 2 mA for 30 minutes over 3 consecutive daily sessions while sham stimulation will be applied for the same duration and timespan. All subjects will complete memory assessments again immediately following each HD-tDCS condition for a total of four test sessions.
This study will probe if the biological changes in amnestic mild cognitive impairment (aMCI) are related to a history of mild traumatic brain injury (mTBI) using high definition transcranial direct current stimulation (HD-tDCS) and blood-derived biomarker tools. Participants who Do as well as those who Do Not have a history of mTBI will be enrolled in the study.