tDCS for Cognitive Improvement in Healthy Subjects

Overseen By Minhtrang Chu

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of California, Davis

Must not be taking: Psychotropic medications

Disqualifiers: Head trauma, Vision issues, Pregnancy, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Approved in 2 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: 20

Duration: 1 month

75 Participants Needed

Trial Summary

Do I need to stop my current medications for the trial?

The trial does not specify if you need to stop taking your current medications, but it excludes those with a history of treatment with psychotropic medication (drugs affecting mood, perception, or behavior).

What data supports the effectiveness of the treatment Transcranial Direct Current Stimulation (tDCS) for cognitive improvement in healthy subjects?

Research shows that tDCS can improve cognitive functions like working memory and reaction time in healthy adults, especially when used repeatedly and paired with tasks. However, the effects can vary widely between individuals. ^{1 2 3 4 5}

Is transcranial direct current stimulation (tDCS) safe for humans?

Research shows that tDCS is generally safe for humans, with no serious or lasting side effects reported in over 33,200 sessions. Common mild effects include itching, tingling, and headaches, which are temporary. ^{6 7 8 9 10}

How does tDCS differ from other treatments for cognitive improvement in healthy subjects?

Transcranial direct current stimulation (tDCS) is unique because it uses a weak electric current applied through the scalp to modulate brain activity, which is different from traditional cognitive enhancement methods that might rely on drugs or behavioral interventions. Unlike other treatments, tDCS is non-invasive and can be administered repeatedly over multiple sessions to potentially enhance cognitive functions like working memory and executive functions. ^{1 2 3 11 12}

What is the purpose of this trial?

The purpose of this study is to better understand the neural correlates of higher-order cognition, both in the healthy brain and in schizophrenia, and to determine how these mechanisms are modulated by transcranial direct current stimulation (tDCS) at frontal and occipital scalp sites. Testing the effects of tDCS at these scalp sites on cognitive task performance will help us understand the roles of the brain regions corresponding to these sites during higher-order cognitive processing (language comprehension, cognitive control, and related attention and memory processes). Behavioral and electrophysiological (EEG) measures will be used to assess cognitive performance. Our overarching hypothesis is that stimulating prefrontal circuits with tDCS can improve cognitive control performance, and ultimately performance on a range of cognitive tasks, as compared to stimulating a different cortical region (occipital cortex) or using sham stimulation. This study is solely intended as basic research in order to understand brain function in healthy individuals and individuals with schizophrenia. This study is not intended to diagnose, cure or treat schizophrenia or any other disease.

Eligibility Criteria

This trial is for healthy individuals aged 18-50 who speak and understand English well enough to complete cognitive tasks. They must be able to consent to the study. People with head trauma, psychotropic medication use, poor vision without correction, or conditions that contraindicate tDCS/MRI (like pregnancy or metal in the body) cannot participate.

Inclusion Criteria

I understand the study and can agree to participate.

I understand the study and can agree to participate.

ability to sufficiently speak and understand English so as to be able to understand and complete cognitive tasks

Exclusion Criteria

I have never had a head injury.

I am not pregnant, have no metal in my body, no serious health issues, no claustrophobia, no metallic implants, no skin conditions at electrode sites, and no brain disorders.

Corrected vision 20/30 or better

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex or occipital cortex, or sham stimulation

1 month

Multiple sessions, each lasting 20 minutes

Follow-up

Participants are monitored for cognitive performance using behavioral and electrophysiological measures

4 weeks

Treatment Details

Interventions

• Transcranial Direct Current Stimulation

Trial Overview The study tests how transcranial direct current stimulation (tDCS) affects higher-order cognition like language comprehension and memory in healthy people and those with schizophrenia. It compares effects of stimulating different brain regions using behavioral tasks and EEG monitoring.

Participant Groups

Group I: Occipital Stimulation Experimental Treatment 1 Intervention

Intervention. 20 minutes of 2 mA direct current stimulation over the occipital cortex.

Group II: DLPFC Stimulation Experimental Treatment 1 Intervention

Intervention. 20 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex.

Group III: Sham Stimulation Placebo Group 1 Intervention

Placebo Comparator. 0.5-1 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex followed by 19-19.5 minutes of sham stimulation

Who Is Running the Clinical Trial?

University of California, Davis

Lead Sponsor

Trials

958

Recruited

4,816,000+

Findings from Research

Anodal transcranial direct current stimulation (tDCS) significantly improved cognitive performance in healthy elderly individuals by increasing neural activity, as evidenced by enhanced P200 and P300 amplitudes during a working memory task.

Cathodal tDCS also showed potential benefits for Alzheimer's disease patients, increasing P200 amplitude and frontal theta activity, suggesting that tDCS can modulate neural function differently based on the individual's cognitive state.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Behavioural and electrophysiological modulations induced by transcranial direct current stimulation in healthy elderly and Alzheimer's disease patients: A pilot study. Cespón, J., Rodella, C., Miniussi, C., et al.[2020]

Transcranial direct current stimulation (tDCS) is a safe and affordable neuromodulatory technique that shows potential for modulating cognitive functioning, particularly in longitudinal studies where repeated sessions are used.

While tDCS has demonstrated some cognitive benefits, the effects are less consistent compared to its impact on motor outcomes, and more research is needed to understand the mechanisms behind its efficacy and to identify which individuals respond best to the treatment.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Cognitive Effects of Transcranial Direct Current Stimulation in Healthy and Clinical Populations: An Overview. Berryhill, ME., Martin, D.[2019]

Transcranial direct current stimulation (tDCS) applied to the left prefrontal cortex significantly improved verbal working memory and naming abilities in healthy adults, with effects lasting for 2 weeks after stimulation.

tDCS targeting the right prefrontal cortex enhanced visuospatial working memory, indicating that different areas of the prefrontal cortex can be stimulated for specific cognitive improvements.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Improvement of the working memory and naming by transcranial direct current stimulation. Jeon, SY., Han, SJ.[2022]

Transcranial direct current stimulation (tDCS) has a small but significant effect on improving reaction times in cognitive tasks for healthy older adults, particularly when applied online during tasks related to learning and memory, as well as executive function.

In contrast, offline tDCS did not show any significant impact on reaction times, indicating that the timing and method of tDCS application are crucial for its efficacy in enhancing cognitive functions in the elderly.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Transcranial direct current stimulation decreased cognition-related reaction time in older adults: A systematic review and meta-analysis. Lee, JH., Lee, TL., Kang, N.[2021]

Transcranial direct current stimulation (tDCS) has shown potential to improve cognitive functions such as processing speed, working memory, and executive functions in patients with mood disorders and schizophrenia, based on a systematic review of 41 studies.

The effects of tDCS on cognitive functioning and memory in Alzheimer's disease and mild cognitive impairment are less clear, with evidence being inconclusive or weak, highlighting the need for standardized protocols in future research.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Transcranial Direct Current Stimulation and Cognition in Neuropsychiatric Disorders: Systematic Review of the Evidence and Future Directions. Ciullo, V., Spalletta, G., Caltagirone, C., et al.[2022]

Transcranial Direct Current Stimulation (tDCS) has been shown to be safe, with no reports of Serious Adverse Effects or irreversible injuries across over 33,200 sessions involving more than 1,000 subjects, including vulnerable populations.

Safety assessments indicate that the current densities used in conventional tDCS (≤4 milliamperes) are significantly lower than those that could potentially cause brain injury, suggesting that tDCS protocols are well within safe limits.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016. Bikson, M., Grossman, P., Thomas, C., et al.[2022]

Transcranial direct current stimulation (tDCS) is generally considered safe, with mild and transient adverse effects reported in clinical trials, but the frequency and relationship of these effects with clinical variables remain unclear due to selective reporting bias.

Out of 209 studies reviewed, 117 mentioned adverse effects, with common issues like itching and tingling reported more frequently in the active tDCS group, although these differences were not statistically significant.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A systematic review on reporting and assessment of adverse effects associated with transcranial direct current stimulation. Brunoni, AR., Amadera, J., Berbel, B., et al.[2022]

Transcranial Direct Current Stimulation (tDCS) is generally considered safe, but there are concerns that it could lead to significant negative effects in healthy individuals.

The scientific community needs to be alerted about the potential risks of tDCS, emphasizing the importance of protecting healthy volunteers from possible harm.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Safety of transcranial direct current stimulation in healthy participants. Boccard-Binet, S., Sen, A.[2021]

High-Definition transcranial Direct Current Stimulation (HD-tDCS) at amplitudes up to 4 mA was well tolerated by 292 older adults, with no safety-related adverse events reported and mostly mild sensations experienced during sessions.

The study demonstrated effective blinding for both participants and researchers, indicating that the sham stimulation was convincing, which supports the use of higher amplitudes for potentially greater therapeutic effects in older adults.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Tolerability and blinding of high-definition transcranial direct current stimulation among older adults at intensities of up to 4 mA per electrode. El Jamal, C., Harrie, A., Rahman-Filipiak, A., et al.[2023]

A systematic review of 64 studies involving 2262 participants found that transcranial direct current stimulation (tDCS) has a low dropout rate (6% for active and 7.2% for sham), indicating good acceptability among participants.

Despite the low dropout rates, many studies inadequately reported adverse events (AEs), highlighting a need for improved guidelines to standardize AE reporting in tDCS research.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A Systematic Review on the Acceptability and Tolerability of Transcranial Direct Current Stimulation Treatment in Neuropsychiatry Trials. Aparício, LVM., Guarienti, F., Razza, LB., et al.[2018]

In a study involving 43 participants, transcranial direct current stimulation (tDCS) targeting the left inferior frontal gyrus did not produce consistent improvements in fluency and working memory tasks, suggesting that the effects of tDCS may be unreliable.

The research highlights the need for further investigation into optimal stimulation parameters and protocols, as current single-session applications may not effectively enhance cognitive performance.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Null Effects on Working Memory and Verbal Fluency Tasks When Applying Anodal tDCS to the Inferior Frontal Gyrus of Healthy Participants. Westwood, SJ., Romani, C.[2020]

In a study involving 40 healthy participants, five sessions of transcranial direct current stimulation (tDCS) significantly enhanced executive functions, as evidenced by improved performance on neuropsychological and behavioral tests.

The tDCS stimulation activated key brain regions associated with executive functions, leading to increased brain activity in the Dorsolateral Prefrontal Cortex and other areas, suggesting a potential mechanism for its effectiveness in cognitive enhancement.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Underpinning the neurological source of executive function following cross hemispheric tDCS stimulation. Abul Hasan, M., Shahid, H., Ahmed Qazi, S., et al.[2023]

References

1. Netherlands pubmed.ncbi.nlm.nih.gov

Behavioural and electrophysiological modulations induced by transcranial direct current stimulation in healthy elderly and Alzheimer's disease patients: A pilot study. [2020]

2. United States pubmed.ncbi.nlm.nih.gov

Cognitive Effects of Transcranial Direct Current Stimulation in Healthy and Clinical Populations: An Overview. [2019]

3. Korea (South) pubmed.ncbi.nlm.nih.gov

Improvement of the working memory and naming by transcranial direct current stimulation. [2022]

4. England pubmed.ncbi.nlm.nih.gov

Transcranial direct current stimulation decreased cognition-related reaction time in older adults: A systematic review and meta-analysis. [2021]

5. United States pubmed.ncbi.nlm.nih.gov

Transcranial Direct Current Stimulation and Cognition in Neuropsychiatric Disorders: Systematic Review of the Evidence and Future Directions. [2022]

6. United States pubmed.ncbi.nlm.nih.gov

Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016. [2022]

7. England pubmed.ncbi.nlm.nih.gov

A systematic review on reporting and assessment of adverse effects associated with transcranial direct current stimulation. [2022]

8. United States pubmed.ncbi.nlm.nih.gov

Safety of transcranial direct current stimulation in healthy participants. [2021]

9. United States pubmed.ncbi.nlm.nih.gov

Tolerability and blinding of high-definition transcranial direct current stimulation among older adults at intensities of up to 4 mA per electrode. [2023]

10. United States pubmed.ncbi.nlm.nih.gov

A Systematic Review on the Acceptability and Tolerability of Transcranial Direct Current Stimulation Treatment in Neuropsychiatry Trials. [2018]

11. Switzerland pubmed.ncbi.nlm.nih.gov

Null Effects on Working Memory and Verbal Fluency Tasks When Applying Anodal tDCS to the Inferior Frontal Gyrus of Healthy Participants. [2020]

12. Netherlands pubmed.ncbi.nlm.nih.gov

Underpinning the neurological source of executive function following cross hemispheric tDCS stimulation. [2023]