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.
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 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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
DIAGNOSTIC
Masking
DOUBLE
Enrollment
75
HD-tDCS for this study is not intended to be a treatment, and will be applied continuously for 30 minutes at sham (0 mA) or 2 mA for active conditions across 3 consecutive daily sessions to probe neural circuit integrity. This specific HD-tDCS device is completely computer driven, running on a laptop using specialized software. Circular electrodes (12-mm in diameter) filled with conductive gel will be placed in a 4x1 ring configuration with the central electrode being the anode surrounded by four cathodes.
University of Texas Southwestern Medical Center
Dallas, Texas, United States
RECRUITINGChanges in Rey Auditory Verbal Learning Test Score
The RAVLT is a verbal episodic memory test that is sensitive to mesial and lateral verbal episodic memory circuit dysfunction. The primary outcome measure for this task is the total number of items immediately recalled during the learning trials and after the 20 minute delayed recall trial. Changes in scores from baseline to testing immediately following the completion of each condition will be examined.
Time frame: Baseline and immediately after completion of each HD-tDCS condition
Changes in Delis Kaplan Executive Function System (DKEFS) Trail Making Test
The DKEFS Trail Making Test is a measure of cognitive flexibility and executive functions. The task requires the subject to as quickly as possible complete five conditions, involving number cancellation, number sequencing, letter sequencing, number-letter switching, and line tracing. The outcome measure for this task is the time to complete each of the five conditions. Changes in scores from baseline to testing immediately following the completion of each condition will be examined.
Time frame: Baseline and immediately after completion of each HD-tDCS condition
Changes in Delis Kaplan Executive Function System (DKEFS) Color-Word Interference Test
The DKEFS Color-Word Interference test is a measure of information processing speed and complex attention. The task requires the subject to as quickly as possible complete four conditions, involving color naming, word reading, response inhibition, and then switching back-and-forth between two response patterns. The outcome measure for this task is the time to complete each of the four conditions. Changes in scores from baseline to testing immediately following the completion of each condition will be examined.
Time frame: Baseline and immediately after completion of each HD-tDCS condition
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