The study will examine the efficacy of high definition transcranial direct current stimulation (HD-tDCS) and its influence on episodic memory in patients with amnestic mild cognitive impairment and a history of Traumatic brain injury. Ten sessions of HD-tDCS to the dorsal anterior cingulate region is expected to result in improvements in episodic memory measures immediately following the last session and at a 3-month follow-up.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
26
This wireless device delivers a very low electrical current to focused regions on the scalp in order to modulate underlying brain circuits to promote neuroplasticity. The device will be fitted onto a neoprene EEG cap, with 1 anode electrode placed and surrounded by 4 cathode electrodes in a ring pattern. Electrical stimulation will be applied using a constant voltage cortical stimulator (Model D185, Digitimer Ltd, UK, maximal output 1000 V/1.5 A) with single square-wave 50-μs pulses (0.1 A/μs rise time).
Sham HD-tDCS
University of Texas Southwestern Medical Center
Dallas, Texas, United States
Hopkins Verbal Learning Test-Revised Total Learning
Episodic verbal memory will be assessed with the Hopkins Verbal Learning Test-Revised (HVLT-R). The HVLT-R is a verbal episodic memory task where a list of 12 words is read aloud for 3 consecutive trials followed by a 20 minute delayed recall trial. The number of items recalled immediately after each trial are summed to create a total learning score, ranging from 0-36. Also, the number of items recalled for the delayed trial are recorded as a delayed recall score, ranging from 0-12. Scores were converted to standardized scores (T-scores) using normative data, ranging from 2-86. Higher scores reflect better episodic memory performance.
Time frame: Baseline, immediately following last HD-tDCS session, and again at 3-month follow-up
Hopkins Verbal Learning Test-Revised Delayed Recall
Episodic verbal memory will be assessed with the Hopkins Verbal Learning Test-Revised (HVLT-R). The HVLT-R is a verbal episodic memory task where a list of 12 words is read aloud for 3 consecutive trials followed by a 20 minute delayed recall trial. The number of items recalled immediately after each trial are summed to create a total learning score, ranging from 0-36. Also, the number of items recalled for the delayed trial are recorded as a delayed recall score, ranging from 0-12. Scores were converted to standardized scores (T-scores) using normative data, ranging from 2-86. Higher scores reflect better episodic memory performance.
Time frame: Baseline, immediately following the last HD-tDCS session, and a 3-month follow-up
Brief Visuospatial Memory Test-Revised (BVMT-R) Total Learning
Episodic verbal memory will be assessed with the Brief Visuospatial Memory Test-Revised (BVMT-R). The BVMT-R is a visual episodic memory task where where an array of 6 simple geometric visual designs are presented in a 2 x 3 matrix for 10 seconds for 3 trials. The number of items recalled immediately after each trial are summed for accuracy and placement to create a total learning score, ranging from 0-36. Also, the number of items recalled for the delayed trial are recorded as a delayed recall score, ranging from 0-12. Scores were converted to standardized scores (T-scores) using normative data, ranging from 2-86. Higher scores reflect better episodic memory performance.
Time frame: Baseline, immediately post-treatment, and a 3 -month follow-up
Brief Visuospatial Memory Test-Revised Delayed Recall
Episodic verbal memory will be assessed with the Brief Visuospatial Memory Test-Revised (BVMT-R). The BVMT-R is a visual episodic memory task where where an array of 6 simple geometric visual designs are presented in a 2 x 3 matrix for 10 seconds for 3 trials. The number of items recalled immediately after each trial are summed for accuracy and placement to create a total learning score, ranging from 0-36. Also, the number of items recalled for the delayed trial are recorded as a delayed recall score, ranging from 0-12. Scores were converted to standardized scores (T-scores) using normative data, ranging from 2-86. Higher scores reflect better episodic memory performance.
Time frame: Baseline, immediately post-treatment, and a 3-month follow-up
Phonemic Fluency
The phonemic verbal fluency task is a measure of language. The subject is required to name as many words as possible that begin with specified letters within 1 minute. Three different letter trials are completed. The outcome measure for this task is the total number of correct responses across the trials, ranging from 0-90. Scores were converted to standardized scores (T-scores) using normative data, ranging from 2-86. Higher scores reflect better performance.
Time frame: Baseline, immediately post-treatment, and a 3-month follow-up
Semantic Fluency
The semantic verbal fluency task is a measure of language and involves 3 conditions. The subject is required to name as many animals as possible within 1 minute. The outcome measure for this task is the total number of correct responses, ranging from 0-90. Scores were converted to standardized scores (T-scores) using normative data, ranging from 2-86. Higher scores reflect better performance.
Time frame: Baseline, immediate post-treatment, and a 3-month follow-up
Trail Making Test
The Trail Making Test is a measure of cognitive flexibility and executive functions. The task requires the subject to as quickly as possible complete two conditions, involving number sequencing and then number-letter switching. The outcome measure for this task is the time in seconds to complete the number-letter switching condition, ranging from 15-300. Scores were converted to standardized scores (T-scores) using normative data, ranging from 2-86. Higher scores reflect better performance
Time frame: Baseline, immediate post-treatment, and a 3-month follow-up
Stroop Color and Word Test
The Stroop Color and Word Test is a measure of information processing speed and complex attention. The task requires the subject to as quickly as possible complete 3 conditions, involving word reading, color naming, and response inhibition. The outcome measure for this task was the response inhibition trial, which is scored as the total correct items completed in the administration time of 45 seconds, ranging from 0-100. Scores were converted to standardized scores (T-scores) using normative data, ranging from 2-86. Higher scores reflect better performance.
Time frame: Baseline, immediate post-treatment, and a 3-month follow-up
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Digit Span Test
The Wechsler Adult Intelligence Scale-4 Digit Span Test measures simple attention and working memory. The examiner reads aloud a series of numbers of increasing length, and individuals are required to repeat each series across 3 separate conditions, involving forwards, backwards, and in sequence. Each trial is scored as incorrect (0) or correct (1), and the total number of correct trials across the 3 conditions are summed, ranging from 0-48. Scores were converted to standardized scores (scaled-scores) using normative data, ranging from 1-19. Higher scores reflect better episodic memory performance
Time frame: Baseline, immediate post-treatment, and a 3-month follow-up