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

40 Participants Needed

Trial Summary

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 data supports the effectiveness of the treatment tDCS for cognitive enhancement in healthy subjects?

Research suggests that tDCS can improve working memory and naming abilities in healthy adults, and it may enhance cognitive performance when used repeatedly, especially when paired with a task. However, the effects can vary, and more studies are needed to fully understand its benefits. ^{1 2 3 4 5}

Is transcranial direct current stimulation (tDCS) safe for healthy individuals?

Research shows that tDCS is generally safe for healthy people, with no serious adverse effects reported in over 33,200 sessions. Common mild side effects include itching, tingling, and headaches, which are usually temporary. ^{3 6 7 8 9}

How does the treatment tDCS differ from other treatments for cognitive enhancement?

Transcranial direct current stimulation (tDCS) is unique because it uses a weak electric current applied through the scalp to modulate brain activity, aiming to enhance cognitive functions like memory and attention. Unlike other treatments that might involve medication or behavioral therapy, tDCS is non-invasive and can be administered repeatedly over multiple sessions to potentially achieve more consistent cognitive benefits. ^{1 2 3 10 11}

What is the purpose of this trial?

Healthy volunteers will be recruited. All subjects will be tested a battery of neuropsychological tests, then undergo fluorodeoxyglucose-positron emission tomography (PET) and magnetic resonance imaging (MRI). During the PET and MRI, they will be stimulated with transcranial direct current stimulation (tDCS) for 15 minutes. A third of subjects will receive real tDCS on the left prefrontal cortex, a third on the right prefrontal cortex, and the other third will receive sham tDCS.

Eligibility Criteria

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

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

Treatment Details

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.

Participant Groups

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+

Findings from Research

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]

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) 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]

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]

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]

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

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

2. 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]

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

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

4. 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]

5. England pubmed.ncbi.nlm.nih.gov

Changes of regional cerebral blood flow after repeated transcranial direct current stimulation in healthy participants: a pilot study. [2023]

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

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

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

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

10. 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]

11. Netherlands pubmed.ncbi.nlm.nih.gov

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