Stimulation to Improve Memory (STIM)

Testing High Definition Transcranial Direct Current Stimulation (HD-tDCS) as Treatment of Mild Cognitive Impairment

This study will test the effects of different doses of a form of non-invasive brain stimulation for the treatment of individuals with mild cognitive impairment (MCI) and dementia of the Alzheimer's Type (DAT).

Study Overview

• Status: Completed
• Conditions: Mild Cognitive Impairment; Dementia of Alzheimer Type
• Intervention / Treatment: Device: Sham; Device: 1 mA HD-tDCS; Device: 2 mA HD-tDCS; Device: 3 mA HD-tDCS

Detailed Description

This research study is being done to learn important information about the effects of weak electrical stimulation on brain functioning in those with mild cognitive impairment (MCI) and dementia of the Alzheimer's type (DAT). The findings will help determine "how much" stimulation is needed to enhance memory and thinking abilities, how it affects brain functioning, and who is most likely to benefit. Ultimately, this information may guide treatment efforts for those at various stages of Alzheimer's disease. The study will use brain imaging to see whether these treatments change how participants learn and remember information. Functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) scans will be used. The study will also use cognitive tests and questionnaires to examine whether participants' memory (and related abilities) change because of treatment. The study will enroll participants with a diagnosis of MCI or DAT. It is expected but not required that participants will be co-enrolled in the University of Michigan Memory and Aging Project (UM-MAP; HUM00000382).

• Study Type: Interventional
• Enrollment (Actual): 233
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Michigan
    • Ann Arbor, Michigan, United States, 48105
      • University of Michigan

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 55 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Diagnosis of Mild Cognitive Impairment (MCI) or dementia of the Alzheimer's type (DAT)
2. Must be MRI compatible, criteria that also apply for High Definition transcranial direct current stimulation (HD-tDCS; e.g., absence of metallic or electronic implants in the upper body or head)
3. Stable on relevant medications for at least 4 weeks prior to study enrollment

Exclusion Criteria:

1. Certain neurological diseases
2. Certain psychiatric conditions
3. Severe sensory impairment

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Sham Comparator: Sham Stimulation; Sham (placebo) dose of HD-tDCS treatment for 30 minutes, for between 5-30 sessions.	Device: Sham; Participants will receive sham (placebo) HD-tDCS for 30 minutes, for between 5-30 sessions.
Experimental: 1 mA Dosage Stimulation; 1 milliAmp dose of HD-tDCS treatment for 30 minutes, for between 5-30 sessions.	Device: 1 mA HD-tDCS; Participants will receive HD-tDCS at 1 mA for 30 minutes, for between 5-30 sessions.
Experimental: 2 mA Dosage Stimulation; 2 milliAmp dose of HD-tDCS treatment for 30 minutes, for between 5-30 sessions.	Device: 2 mA HD-tDCS; Participants will receive HD-tDCS at 2 mA for 30 minutes, for between 5-30 sessions.
Experimental: 3 mA Dosage Stimulation; 3 milliAmp dose of HD-tDCS treatment for 30 minutes, for between 5-30 sessions.	Device: 3 mA HD-tDCS; Participants will receive HD-tDCS at 3 mA for 30 minutes, for between 5-30 sessions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Lateral Temporal Cortex Connectivity	Primary outcome focuses on default mode network (DMN) between-network functional connectivity because the lateral temporal cortex is a core component of the DMN. Between-network functional connectivity is estimated from fMRI data as strength of temporal coupling between the DMN and other high-level (association) brain networks. For each participant and time point, correlation-based connectivity (Pearson r; Fisher r-to-z transformed; arbitrary units) computed between DMN regions and other regions of the association cortex defined using standard functional atlas. Higher values reflect stronger functional connectivity between DMN and other regions. A Z-score's range is infinite. Expected value is between -3 to 3. Analyses conducted separately for amyloid negative (A-) and amyloid positive (A+) participants. Post Intervention data collection was on day 5 of treatment. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks, longest was 43 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Self-Report of Contentment With Memory	The Multifactorial Memory Questionnaire (MMQ) consists of three scales measuring separate aspects of metamemory. Items are rated on a 5-point Likert scale (0-4) based on the test taker's experiences over the previous two weeks. MMQ-Satisfaction (formerly called MMQ-Contentment) scale measures satisfaction, concern, and overall appraisal of one's own memory. Each of 18 statements is rated based on degree of agreement. The score range is 0 to 72, with higher scores indicating a higher degree of satisfaction. Post Intervention data collection was on day 5 of treatment. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks, longest was 43 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).
Self-Report of Memory Mistakes	Multifactorial Memory Questionnaire (MMQ) Ability Score - This scale measures self-perception of everyday memory ability. Respondents rate how often they experienced each of 20 common memory mistakes over the previous two weeks. The score range is 0 to 80, with higher scores indicating better self-reported memory ability. Post Intervention data collection was on day 5 of treatment. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks, longest was 43 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).
Self-Report of Memory Strategies Used	Multifactorial Memory Questionnaire (MMQ) Strategies Score - This scale measures the use of practical memory strategies and aids in day-to-day life. Respondents rate how often they used each of 19 memory strategies over the previous two weeks. The score range is 0 to 76, with higher scores indicating greater use of memory strategies. Post Intervention data collection was on day 5 of treatment. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks, longest was 43 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).
Change in Memory Functioning	The Repeatable Battery of the Assessment of Neuropsychological Status (RBANS) is a comprehensive neuropsychological battery for the evaluation of global cognition. The delayed memory section is a measure of delayed recall and recognition for verbal and visual information. It includes the subtests List Recall, List Recognition, Story Memory, and Figure Recall. Low scores on this index indicate difficulties with recognition and retrieval of information from long-term memory stores This index is composed of both auditory and visual measures; therefore, a severe deficit in language, auditory processing, or visual functioning may impact one of the measures more than the other. Analysis included the sum of the raw scores for each of the delayed memory subtests, with possible scores ranging from 0 to 62. Post Intervention data collection was on day 5 of treatment. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks, longest was 43 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).
Change in Overall Fluid Cognitive Abilities	Cognitive function was determined using the NIH Toolbox-Cognition Battery computerized tests, specifically the Fluid composite score. It is derived by averaging the subtests in the Fluid domain to achieve an overall standard score. Fully Corrected T-scores are adjusted for for age, gender, race/ethnicity, and educational attainment. The score compares the score of the participant to those in the NIH Toolbox nationally representative normative sampling. The T-score has a mean of 50 in the general population and a SD of 10. Scores higher than the mean indicate better performance. Post Intervention data collection was on day 5 of treatment. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks, longest was 43 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).
Cumulative Working Memory Effects of HD-tDCS Across Treatment Sessions	The n-back test is a working memory task where participants identify stimulus that matches stimulus experienced "n" steps back. Participants performed a 2-back test, in which they were asked to remember and press a button when shown a stimulus that appeared 2 steps before the current one (e.g. square, circle, square). The number of correct and incorrect identifications are normalized (z-score). Total score is the z-score of correct button presses minus the z-score of incorrect button presses. A higher score (d') reflects better working memory performance. Possible scores range from -4.85 to 4.85. Positive change (increase) in 2-back score across treatment sessions indicates improvement in working memory performance. Data is shown as the mean slope calculation of participants across first 5 days of treatment and across all treatments, x=days of treatment, y=n-back score. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).
Cumulative Memory Accuracy Effects of HD-tDCS Across Treatment Sessions	Paired Associates task is a verbal memory task that asks participants to learn a list of word pairs. After a delay, participants are shown correct and mismatched word pairs one at a time and asked to identify if the displayed word pair was from the list they were asked to learn or not. Total accuracy is a proportion (total correct responses divided by total trials completed) ranging from 0 to 1 that measures the accuracy of a participant's responses to both correct and mismatched word pairs. Higher scores indicate better verbal memory performance, and positive changes over time indicate an improvement in verbal memory performance, measured after baseline (Session 1) and every intervention session (Sessions 2-5) Data is shown as the mean slope calculation of participants across first 5 days of treatment and across all treatments, x=days of treatment, y= total accuracy. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).
Cumulative Memory Sensitivity Effects of HD-tDCS Across Daily Sessions	Verbal memory performance for computerized Paired Associates task, summarized with a computational model (linear ballistic accumulator decision model). The model uses each participant's accuracy and reaction times across trials to estimate how efficiently they accumulate information to distinguish previously studied (target) word pairs from new (lure) pairs. Reported outcome is the average memory sensitivity score at baseline, expressed as unitless model values (scores on a scale) where higher scores indicate better discrimination, scores near zero indicate chance-level performance, and negative scores (if present) indicate performance worse than chance.	Baseline
Tolerability of HD-tDCS	Tolerability was assessed using the HD-tDCS Safety Questionnaire, an 11-item symptom checklist. The questionnaire assesses the presence (yes/no) of 10 specific self-reported symptoms (Itching, Burning, Tingling, Scalp Pain, Trouble Concentrating, Sleep problems, Headache, Mood Change, Neck Pain, and Other symptoms) and 1 oberserved symptom, Skin Redness. Skin Redness was excluded from this analysis as it is not related to the participant's perception of tolerability. The total score (symptom burden) was calculated by summing the number of symptoms present across the 10 items for each session. Score range: 0 to 10 symptoms, where 0 = no symptoms present and 10 = all symptoms present. Higher scores indicate worse tolerability (more symptoms experienced). Values represent the mean number of symptoms per session, calculated by averaging symptom burden scores across all post-stimulation assessments within each treatment group.	Assessed immediately after each HD-tDCS session (participants received up to 30 sessions over approximately 1-12 weeks); values represent mean symptom burden averaged across all post-stimulation assessments
Effectiveness of Blinding of HD-tDCS	Participant's perception of treatment assignment assessed after each stimulation session using a 3-category ordinal scale. Participants guessed whether they received: (0) Sham stimulation, (1) Don't Know, or (2) Active stimulation. The scale is ordinal with Sham < Don't Know < Active. Effective blinding is indicated by no significant difference in the distribution of perceived assignment between active and sham groups (i.e., participants in active groups cannot reliably distinguish their treatment from sham). Higher proportional odds ratios would indicate active group participants were more likely to guess "active"; lower ratios would indicate sham participants were more likely to guess "active" (paradoxical pattern suggesting convincing sham condition).	Assessed immediately after each HD-tDCS session (participants received up to 30 sessions over approximately 1-12 weeks)
Change in Default Mode Network Connectivity	The outcome focuses on default mode network (DMN) within-network functional connectivity. Within-network functional connectivity is estimated from fMRI data as strength of temporal coupling within DMN regions (nodes). For each participant and time point, correlation-based connectivity (Pearson r; Fisher r-to-z transformed; arbitrary units) was computed between DMN regions defined using a standard functional atlas. Higher values reflect stronger functional connectivity within DMN. A Z-score's range is infinite. Expected value is around -3 to 3. Analyses are conducted separately for amyloid negative (A-) and amyloid positive (A+) participants. Post Intervention data collection was on day 5 of treatment. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks, longest was 43 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).
Cumulative Cognitive Change Across Daily Consecutive Sessions	Measured through change in Cogstate or other comparable computerized cognitive testing scores across consecutive daily sessions.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).
Change in Global Cognition	The Repeatable Battery of the Assessment of Neuropsychological Status (RBANS) is a comprehensive neuropsychological battery for the evaluation of global cognition and has been validated in subjects with mild cognitive impairment, moderate to severe traumatic brain injuries, vascular dementias, and Alzheimer's disease. Data was analyzed using the sum of the subtest raw scores, which is an indicator of the general cognitive functioning of the examinee. Low scores suggest general cognitive impairment even when some individual subtest scores may be within normal limits. Individuals with low scores on this measure exhibit problems with attention, memory, language, and construction skills. Possible scores range from 0 to 321. Post Intervention data collection was on day 5 of treatment. Post-Expansion (PE) appointments were not consecutive. Mean time between enrollment and PE was 10 wks, longest was 43 wks.	Change from Baseline to Post-Intervention (after tDCS Session 5 - day 5 of treatment) and from Baseline to Post-Expansion (after the participant's final tDCS session beyond Session 5, up to 43 weeks).

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Inhibition Ability	A priori intent to measure through change in the NIH Toolbox Flanker Inhibitory Control and Attention Test Score	Baseline and post-intervention (after tDCS sessions 5 & 30)
Change in Conceptualization Ability	A priori intent to measure through change in the NIH Toolbox Dimensional Change Card Sort Test Score	Baseline and post-intervention (after tDCS sessions 5 & 30)
Change in Picture Sequence Memory	A priori intent to measure through change in the NIH Toolbox Picture Sequence Memory Test Score	Baseline and post-intervention (after tDCS sessions 5 & 30)
Change in Working Memory Ability	A priori intent to measure through change in the NIH Toolbox List Sorting Working Memory Test Score	Baseline and post-intervention (after tDCS sessions 5 & 30)
Change in Processing Speed	A priori intent to measure through change in the NIH Toolbox Pattern Comparison Processing Speed Test Score	Baseline and post-intervention (after tDCS sessions 5 & 30)
Change in Visuospatial Functioning	Measured through change in the RBANS Visuospatial Index score	Baseline and post-intervention (after tDCS sessions 5 & 30)
Change in Language Functioning	Measured through change in the RBANS Language Index score	Baseline and post-intervention (after tDCS sessions 5 & 30)
Change in Attention	Measured through change in the RBANS Attention Index score	Baseline and post-intervention (after tDCS sessions 5 & 30)
Change in Memory Functioning	Measured through change in the RBANS Immediate Memory Index score	Baseline and post-intervention (after tDCS sessions 5 & 30)
Change in Cognitive Functioning	A priori intent to measure through changes in RBANS subtest scores	Baseline and post-intervention (after tDCS sessions 5 & 30)

Collaborators and Investigators

• Sponsor: University of Michigan
• Collaborators: National Institute on Aging (NIA)
• Investigators: Principal Investigator: Benjamin Hampstead, PhD, Associate Professor

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2019
• Primary Completion (Actual): December 6, 2024
• Study Completion (Actual): December 19, 2024

Study Registration Dates

• First Submitted: March 11, 2019
• First Submitted That Met QC Criteria: March 13, 2019
• First Posted (Actual): March 14, 2019

Study Record Updates

• Last Update Posted (Actual): July 2, 2026
• Last Update Submitted That Met QC Criteria: June 29, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: PET scan; Dementia; fMRI; Memory; Cognitive Rehabilitation; Brain Stimulation
• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Mental Disorders; Neurocognitive Disorders; Cognition Disorders; Cognitive Dysfunction; Dementia
• Other Study ID Numbers: HUM00146180; 1R01AG058724 (U.S. NIH Grant/Contract)

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