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Effect of Electrical Stimulation (DC Polarization) to the Brain on Memory

This study has been completed.
Information provided by (Responsible Party):
National Institutes of Health Clinical Center (CC) ( National Institute of Neurological Disorders and Stroke (NINDS) ) Identifier:
First received: May 8, 2007
Last updated: March 23, 2016
Last verified: March 2013

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.

Condition Intervention Phase
Device: DC brain polarization
Phase 1
Phase 2

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Participant, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Effect of Direct Current Brain Polarization on Verbal Memory

Resource links provided by NLM:

Further study details as provided by National Institutes of Health Clinical Center (CC):

Primary Outcome Measures:
  • Verbal Memory [ Time Frame: 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).

Enrollment: 45
Study Start Date: May 2007
Study Completion Date: April 2010
Primary Completion Date: April 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Sham Comparator: Sham TDCS Device: DC brain polarization
0.08 mA/cm2
Experimental: Surface-anodal direct current
0.08 mA/cm2
Device: DC brain polarization
0.08 mA/cm2
Active Comparator: Surface-cathodal direct current
0.08 mA/cm2
Device: DC brain polarization
0.08 mA/cm2

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.


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Healthy volunteers over age 18. Pregnancy is not an exclusion.


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.

  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00471107

United States, Maryland
National Institutes of Health Clinical Center, 9000 Rockville Pike
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
National Institute of Neurological Disorders and Stroke (NINDS)
  More Information

Responsible Party: National Institute of Neurological Disorders and Stroke (NINDS) Identifier: NCT00471107     History of Changes
Other Study ID Numbers: 070147
Study First Received: May 8, 2007
Results First Received: January 17, 2012
Last Updated: March 23, 2016

Keywords provided by National Institutes of Health Clinical Center (CC):
Frontal Lobe
Healthy Volunteer
HV processed this record on April 25, 2017