tDCS for Cognitive Enhancement in Healthy Subjects

(Normal_tDCS Trial)

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of Manitoba

Disqualifiers: Neurological, Psychiatric, Hypertension, Cardiovascular, others

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

Compensation: Varies

Number of Visits: 2

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to explore how transcranial direct current stimulation (tDCS) might boost brain power in healthy individuals. Participants will undergo brain scans while receiving tDCS, which applies a gentle electric current to different parts of the brain. Some participants will receive real stimulation on either the left or right side of the brain, while others will receive a fake version for comparison. This trial suits healthy individuals without a history of neurological or psychiatric conditions and who are free of metal implants. As an unphased trial, it offers participants the opportunity to contribute to groundbreaking research in cognitive enhancement.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications.

What prior data suggests that this tDCS technique is safe for cognitive enhancement in healthy subjects?

Research has shown that transcranial direct current stimulation (tDCS) is generally safe and easy to manage. Studies on applying tDCS to the left side of the brain's front area, known as the dorsolateral prefrontal cortex (DLPFC), have found it safe and practical, even for older adults. Similarly, research on the right side of this brain area indicates that the treatment is well tolerated, with only mild side effects like slight tingling or itching during the session. These studies have reported no major negative effects. Overall, evidence suggests that tDCS is a safe method for non-invasive brain stimulation. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about tDCS (transcranial direct current stimulation) for cognitive enhancement because it offers a non-invasive method to potentially boost brain function by applying low electrical currents to specific areas of the brain. Unlike traditional cognitive enhancement techniques that might involve medication or extensive cognitive training, tDCS targets the dorsolateral prefrontal cortex directly, which is thought to play a crucial role in executive functions like problem-solving and memory. This method could provide quicker, more flexible cognitive improvements without the need for pharmaceuticals, which often come with side effects. Additionally, the ability to stimulate either the left or right side of the brain allows for tailored interventions based on individual cognitive needs.

What evidence suggests that tDCS is effective for cognitive enhancement?

This trial will compare different applications of transcranial direct current stimulation (tDCS) for cognitive enhancement in healthy subjects. Research has shown that tDCS can effectively improve brain functions. In this trial, some participants will receive real tDCS on the left dorsolateral prefrontal cortex, which studies indicate can enhance skills like hand coordination and improve performance on tasks involving movement. Others will receive real tDCS on the right dorsolateral prefrontal cortex, which has shown significant improvements in social communication and thinking skills in children with autism, suggesting wider benefits for the brain. Additionally, a sham tDCS arm will serve as a comparison. Overall, tDCS has shown promise in enhancing various mental abilities, supporting its use for improving brain function in healthy individuals. ^{2 6 7 8 9}

Are You a Good Fit for This Trial?

This trial is for healthy volunteers without any history of neurological or psychiatric diseases, abnormal MRI results, metal implants, pacemakers, severe hypertension, cardiovascular disease or family history of epilepsy. Pregnant or breastfeeding women are also excluded.

Exclusion Criteria

You have very high blood pressure.

Pregnant or breastfeeding women (female subjects of child bearing potential will be screened for pregnancy before MRI imaging)

You have an unusual MRI result.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Neuropsychological Testing

Participants undergo a battery of neuropsychological tests

1 day

1 visit (in-person)

Imaging and Stimulation

Participants undergo PET and MRI scans with tDCS stimulation

1 day

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after imaging and stimulation

1-2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• tDCS

Trial Overview The study tests the effects of transcranial direct current stimulation (tDCS) on brain function. Participants will undergo neuropsychological tests and brain imaging while receiving either real tDCS to left or right prefrontal cortex or sham (fake) tDCS.

How Is the Trial Designed?

Group I: Real Left DLPFC tDCS Active Control 1 Intervention

Real tDCS on the left dorsolateral prefrontal cortex

Group II: Real Right DLPFC tDCS Active Control 1 Intervention

Real tDCS on the right dorsolateral prefrontal cortex

Group III: Sham tDCS Placebo Group 1 Intervention

30sec ramp-up and 30sec ramp-down

Who Is Running the Clinical Trial?

University of Manitoba

Lead Sponsor

Trials

628

Recruited

209,000+

Published Research Related to This Trial

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]

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]

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]

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) 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) 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) 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]

In a pilot study involving five healthy adults, repeated transcranial direct current stimulation (tDCS) significantly improved regional cerebral blood flow in the right superior frontal gyrus, suggesting potential cognitive enhancement.

The tDCS sessions were well-tolerated with no reported adverse events, indicating a safe application of this technique for enhancing brain function.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Changes of regional cerebral blood flow after repeated transcranial direct current stimulation in healthy participants: a pilot study. Jeong, H., Song, IU., Chung, YA., et al.[2023]

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]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11541428/

Transcranial direct current stimulation and its effect on ... Recent studies indicate that tDCS can significantly improve cognitive functioning in individuals with schizophrenia, with effects persisting ...

2. translational-medicine.biomedcentral.com translational-medicine.biomedcentral.com/articles/10.1186/s12967-023-03989-9

Transcranial direct current stimulation to the left dorsolateral ... In this study, using the PPT, we tested the impact of tDCS on the left DLPFC and found that it improved early-phase manual dexterity skills ...

3. sciencedirect.com sciencedirect.com/science/article/pii/S0165178124005936

Transcranial direct current stimulation (tDCS) enhances ... We concluded that tDCS can enhance cognition and generate a satisfactory perception of cognitive improvement in patients with schizophrenia.

4. frontiersin.org frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2022.890963/full

Transcranial Direct Current Stimulation of the Dorsolateral ... These results suggest that a single tDCS session of the left DLPFC can improve the performance of cognitive tasks complementary to motor execution, but not on ...

5. nature.com nature.com/articles/s41537-025-00647-5

Investigating the effects of transcranial direct current ... First studies in healthy participants reported that excitatory, anodal tDCS to the DLPFC can effectively enhance WMT, with effects lasting up to ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC2754807/

Establishing safety limits for transcranial direct current ... Go-no-go task performance improvement after anodal transcranial DC stimulation of the left dorsolateral prefrontal cortex in major depression. J Affect ...

7. sciencedirect.com sciencedirect.com/science/article/pii/S2590109523000447

Feasibility and Safety of Sequential Transcranial ... This study provides preliminary evidence about the feasibility, safety, and challenges to combine PT and tDCS in very frail older adults.

8. frontiersin.org frontiersin.org/journals/neurology/articles/10.3389/fneur.2022.821286/full

Efficacy of Transcranial Direct Current Stimulation Over ... Our findings indicated that tDCS over DLPFC could serve as a potentially effective therapy for improving the consciousness state in patients with MCS.

9. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11549028/

Effects of Transcranial Direct Current Stimulation Targeting ... In conclusion, the tDCS targeting DLPFC may be a potentially effective therapeutic target for alleviating somatic symptoms in patients with MDD.