Effects of tDCS on Cognition in MCI: A RCT

October 13, 2022 updated by: Michael Chih Chien KUO, PhD, Tung Wah College

Effects of Transcranial Direct Current Stimulation (tDCS) on Cognition in Older Adults With Mild Cognitive Impairment: A Randomized Controlled Trial

MCI is considered an intermediate stage between normal cognitive aging and dementia. As such, improving cognitive functions of people with MCI may delay dementia onset. In recent years, tDCS, which regulates brain activity by increasing or decreasing brain tissue excitability, has become a commonly used brain stimulation method. Accumulating evidence indicates the promising effects of cognitive enhancement after tDCS over the frontal scalp regions in people with MCI (PwMCI). However, previous studies were limited by including only a self-report measure, focused on memory performance, not assessing long-term effect, and not reporting their results in follow-up. In addition, knowledge of the precise physiological consequences of tDCS on the brain tissue and related neural mechanisms in PwMCI remains rudimentary. The objectives of the proposed study, which will target PwMCI, are to investigate the effects of tDCS at the left dorsolateral prefrontal cortex on the cognitive performance and to explore the modulation of neural mechanisms associated with the use of tDCS. Forty-eight MCI participants aged over 60 years will be recruited. All participants will be assessed by Hong Kong version of Montreal Cognitive Test. Participants that meet selection criteria will be invited to the experiment. Participants will be assigned to experimental or control groups randomly. The experiment will consist of pre- and post-assessments and a 1-month follow-up assessment. Between pre- and post-assessments, participants will receive 8 sessions (2x/week for 4 weeks) of tDCS treatment (either real or sham, 20 min per session). Outcome measures include digit span test, colour trail test, verbal fluency test, Chinese version of the Verbal Learning Test , and Hong Kong version of Montreal Cognitive Assessment. Participants will also complete a computer memory task at each assessment point (performance in this task is also used as an outcome measure) and will have their brain wave recorded while completing the task. The task will require them to study and memorise Chinese characters, followed by a recognition memory test. In the study phase, participants will be required to view Chinese characters and judge whether the characters are of the animal category. In the recognition phase, participants will decide whether the characters have been seen before.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Randomization and blinding Due to limited available resources and the time required to collect the data, the investigators plan to implement the experiment in 4 batches, each separated by approximately two months. Each batch will include 12 participants from the same recruiting site. Six of them will be assigned to the anodal group and the other six to the sham group, using the block randomization method provided by http://www.randomization.com. The online software generates group allocation by knowing the number of participants per block (6) and number of blocks (2). Only the principal investigator will know the group assignments. Neither the participants nor the assessors will be given the information regarding the group assignments. Each participant will be given a registration number by the Principal Investigator. The tDCS device can be set to anodal or sham status. The PI will set up the tDCS device (anodal or sham) according to the participant's registration number and group through the device's administration menu. The research associate will select the stimulation protocol by inputting the participant's registration number on the device and be blinded to the participant's group assignment when performing tDCS stimulation and other assessments.

Sample size calculation The investigators used G*Power software to estimate the number of participants required to conduct repeated measure analyses of variance (within-between interactions) using the following parameters: correlation among repeated measures = 0.5, alpha = 0.05, number of groups = 2, power = 0.9 and number of measurements = 3 (assuming the correlation between repeated measures = 0.9). Effect size f is conservatively assumed to be 0.25. Based on previous experience using tDCS on participants with dementia and previous relevant studies, the investigators assumed a retention rate of 75%. Thus, the required sample size would be 48.

Procedure This proposed investigation will use a sham-controlled, randomized controlled trial. Participants will be randomly assigned to the anodal or sham groups (in 1:1 ratio). The stimulation method (anodal/sham) will be designated as the between-subject factor (independent variable). The potential participants will be screened and those who meet the selection criteria will be invited to participate in the study. Participants will attend a baseline assessment session in which the collection of demographic information, neurocognitive assessment scores, and a computer task with EEG recorded will occur, followed by 8 sessions of anodal tDCS completed twice a week for 4 weeks. Multi-session tDCS studies usually have a varied intervention schedule from 1 to 5 sessions per week for 1 to 5 weeks. The investigators have opted for this schedule to balance the time spent on intervention with its potential effectiveness, and to encourage compliance. After the intervention, participants will receive post- and 1-month follow-up assessments which will be the same as the baseline assessment.

EEG data acquisition EEGs will be recorded from 64 Ag/AgCl electrodes (BioSemi Active Two) located on the standard scalp sites of the 10/20 system. Four electrodes will be used to monitor eye blinks and movements. Two other electrodes will be placed in the mastoids for the EEG signal to be re-referenced off-line. Scalp EEG will be recorded from F3. Curry 9 software (Neuroscan Compumedics, U.S.A), or newer, will be used for the EEG signal processing. The EEGs will be sampled at 1024 Hz, with a low-pass filter of -200 μV. Digital band-pass filtering from 0.1 Hz to 30 Hz will be applied off-line. The continuous EEG signals will be segmented into epochs, from 200 ms before the stimulus to 1500 ms after the stimulus onset, and then the baseline will be corrected to the pre-stimulus interval. The epochs with amplitude ± 75 μV will be omitted from averaging. The averaged ERPs will be computed for each participant by classifying the study epochs that are correctly identified subsequently or missed during the recognition phase. Using the Curry 9 software, these averaged ERP files will then be transformed into text files with voltage (μV) and temporal information (ms) that can be read by Microsoft Excel software. After further rearrangement and processing in Excel, the data will be transferred to SPSS software for statistical analysis.

Study Type

Interventional

Enrollment (Anticipated)

48

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

60 years and older (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • inexperienced with tDCS
  • normal or corrected-to-normal vision
  • right-handed
  • independent in activities of daily living
  • no history of seizures, head injuries, migraine, epilepsy or other psychiatric or neurological conditions

Exclusion Criteria:

  • taking medication or supplements known to affect cognition (such as Ginkgo)
  • exhibiting symptoms of emotional disorders
  • having a history of cerebrovascular surgery
  • with a metal plate in their skull

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: TREATMENT
  • Allocation: RANDOMIZED
  • Interventional Model: PARALLEL
  • Masking: DOUBLE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
EXPERIMENTAL: Simulation group
During anodal stimulation, the participants will receive 1.5 mA of constant current over the site for 20 min, with a 15-second ramp up and scale down at the beginning and the end of the procedure.
Device: transcranial direct current stimulation
tDCS is planned to be administered via electrodes positioned over the left dlPFC (anodal/sham electrode) and the left supraorbital area (reference electrode).
SHAM_COMPARATOR: Sham group
In the sham stimulation condition, the current will only be administered during the first 30 seconds and last 30 seconds of the 20-minute window.
Device: transcranial direct current stimulation
tDCS is planned to be administered via electrodes positioned over the left dlPFC (anodal/sham electrode) and the left supraorbital area (reference electrode).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Digit span test (Wechsler & De Lemos, 1981)
Time Frame: 2 minutes
Participants are presented with a random series of digits, and are asked to repeat them in the order presented.
2 minutes
Colour Trail Test (CTT) (D' Elia et al., 1996)
Time Frame: 8 minutes

CTT1: Must be administered first and requires the respondent to connect circles in an ascending numbered sequence (1-25).

CTT2: Must follow the CTT1 and requires the respondent to connect numbers in an ascending sequence while alternating between pink and yellow colors.
8 minutes
verbal fluency test (Lezak et al., 2004)
Time Frame: 3 minutes
Participants produce as many words as possible from a category in 60 seconds.
3 minutes
Chinese version of the Verbal Learning Test (Chang et al., 2010)
Time Frame: 10 minutes
Participants repeat 9 Chinese words after they are presented.
10 minutes
Hong Kong version of Montreal Cognitive Assessment (Yeung et al., 2014)
Time Frame: 15 minutes
A screening tool for MCI
15 minutes
Computerized memory task
Time Frame: 40 minutes
During the study phase of the memory task, the participants will view the Chinese words on a computer screen and decide whether they are from the animal category. After finishing the study/encoding phase, the participants will perform the recognition/test task. During this task, the participants will view characters and judge whether they had seen them previously in the study phase.
40 minutes
Event-related potential
Time Frame: 40 minutes
Electroencephalograms are recorded while completing the computerized memory task
40 minutes

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Geriatric Depression Scale (Chiu et al., 1994)
Time Frame: 5 minutes
This is a screening test for major depression. There are 15 items. Cut off score is 7/8.
5 minutes

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Tung Wah College

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (ANTICIPATED)

June 1, 2023

Primary Completion (ANTICIPATED)

May 1, 2025

Study Completion (ANTICIPATED)

May 1, 2026

Study Registration Dates

First Submitted

October 10, 2022

First Submitted That Met QC Criteria

October 13, 2022

First Posted (ACTUAL)

October 18, 2022

Study Record Updates

Last Update Posted (ACTUAL)

October 18, 2022

Last Update Submitted That Met QC Criteria

October 13, 2022

Last Verified

October 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • UGC/FDS17/M06/22

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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