Healthy
Conditions
Keywords
Frontal Lobe, Language, Dementia, Healthy Volunteer, HV
Brief summary
This study will test the effect of direct current (DC) brain polarization (the application of a very weak electrical current to the brain) on learning and memory. Earlier studies have shown that DC polarization can temporarily improve the ability of healthy people to think of certain words. This study will explore whether it can also temporarily improve learning and memory. Healthy people 18 years of age and older may be eligible for this study. Subjects participate in two experimental sessions at the NIH Clinical Center. The first session lasts about 1 hour; the second session, on the next day, takes about 10 minutes. At the beginning of the first session, electrodes are placed on the subject's head and arm for brain stimulation. The current may be turned on for 25 minutes, or only very briefly (sham stimulation). Subjects are not told which type of stimulation they are receiving. No stimulation is applied in the second session. During the sessions subjects are asked to complete the following tasks that will help elucidate the effects of polarization: * Read a list of words and remember them. Later they will try to repeat the words from memory. * Look at a series of designs and remember them. Later they will try to draw the designs from memory. * Push a button on a keyboard when they see a specific item (for example, when the number 7 appears). * Generate as many words as they can think of that begin with a particular letter of the alphabet. Subjects may be videotaped for some or all of the time during the sessions.
Detailed description
OBJECTIVE: The principal objective is to establish whether DC polarization of left lateral prefrontal cortex can enhance verbal memory. STUDY POPULATION: 75 healthy volunteers over the age of 18 will be enrolled. DESIGN: The study is a double-blind parallel study with three arms: anodal polarization, cathodal polarization, and sham treatment. OUTCOME MEASURES: The primary outcome measure is performance on the WMS-III Word Lists test. Secondary outcome measures, testing for effects of DC polarization on basic information processing and non-verbal memory, respectively, are the CalCAP and WMS-III Visual Reproduction Test. The Verbal Fluency Test will be administered prior to stimulation and 24 hours post-stimulation to screen for other residual effects of the polarization on the stimulated region.
Interventions
DEVICEDC brain polarization
0.08 mA/cm2
Sponsors
National Institute of Neurological Disorders and Stroke (NINDS)
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* INCLUSION CRITERIA: Healthy volunteers over age 18. Pregnancy is not an exclusion.
Exclusion criteria
Any history of a central nervous system illness or other behavioral disorder. Broken skin in the area of the electrodes. Uncontrolled medical problems, such as diabetes mellitus, hypertension, airway disease, heart failure, coronary artery disease, or any other condition that poses a risk for the subject during participation. Presence of metal in the cranial cavity. Holes in the skull made by trauma or surgery.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Verbal Memory | 24 hours | The Wechsler Memory Scale (WMS-III) is a neuropsychological test designed to measure different memory functions. The WMS-III Word Lists is a measure of verbal learning ability. The examiner reads a list of 12 semantically unrelated words and the subject immediately recalls as many words as possible. For this study, the primary outcome is a measure of verbal recall performance at 24 hours following presentation of the words under three conditions, i.e., anodal tDCS, cathodal tDCS, and sham. Scores may range from 0 (no words recalled) to 12 (all words recalled). |
Countries
United States
Participant flow
Recruitment details
Healthy subjects were recruited through the NIH Clinical Research Volunteer Program
Pre-assignment details
Nothing to report
Participants by arm
| Arm | Count |
|---|---|
| Anodal TDCS Randomly selected healthy volunteers undergoing left dorsolateral prefrontal cortex (LDPFC) anodal transcranial direct current stimulation (tDCS) during verbal memory tasks. | 12 |
| Cathodal TDCS Randomly selected healthy volunteers undergoing left dorsolateral prefrontal cortex (LDPFC) cathodal transcranial direct current stimulation (tDCS) during verbal memory tasks. | 14 |
| Sham TDCS Randomly selected healthy volunteers undergoing left dorsolateral prefrontal cortex (LDPFC) sham stimulation during verbal memory tasks. | 12 |
| Total | 38 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 | FG002 |
|---|---|---|---|---|
| Overall Study | Technical problems/data loss | 3 | 1 | 3 |
Baseline characteristics
| Characteristic | Anodal TDCS | Cathodal TDCS | Sham TDCS | Total |
|---|---|---|---|---|
| Age, Continuous | 26.5 years STANDARD_DEVIATION 8.06 | 32.4 years STANDARD_DEVIATION 14.05 | 32.5 years STANDARD_DEVIATION 11.29 | 30.57 years STANDARD_DEVIATION 11.6 |
| Sex: Female, Male Female | 5 Participants | 6 Participants | 8 Participants | 19 Participants |
| Sex: Female, Male Male | 7 Participants | 8 Participants | 4 Participants | 19 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk |
|---|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — | — / — |
| other Total, other adverse events | 0 / 12 | 0 / 14 | 0 / 12 |
| serious Total, serious adverse events | 1 / 12 | 0 / 14 | 0 / 12 |
Outcome results
Primary
Verbal Memory
The Wechsler Memory Scale (WMS-III) is a neuropsychological test designed to measure different memory functions. The WMS-III Word Lists is a measure of verbal learning ability. The examiner reads a list of 12 semantically unrelated words and the subject immediately recalls as many words as possible. For this study, the primary outcome is a measure of verbal recall performance at 24 hours following presentation of the words under three conditions, i.e., anodal tDCS, cathodal tDCS, and sham. Scores may range from 0 (no words recalled) to 12 (all words recalled).
Time frame: 24 hours
Population: All subjects in this group for whom data were obtained were analyzed
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Left Prefrontal Anodal TDCS | Verbal Memory | 8.625 Words recalled | Standard Deviation 1.768 |
| Left Prefrontal Cathodal TDCS | Verbal Memory | 9 Words recalled | Standard Deviation 1.604 |
| Sham TDCS | Verbal Memory | 8 Words recalled | Standard Deviation 2.828 |
Comparison: Power analysis was based on WMS-III Word Lists performance. With an effect comparable to the effect on verbal fluency in an earlier study of left frontal TDCS in healthy subjects, it would require 10 subjects per group (30 total) for a significance level of 0.05 and 80% power.p-value: >0.05ANOVA