tES Effects on Associative Memory Performance

Effects of Transcranial Electric Stimulation on Associative Memory Formation in Healthy Elderly Participants as Well as in Individuals With Memory Impairment

Previous studies showed that transcranial electric stimulation (tES) applied over the prefrontal cortex improves cognitive performance in healthy elderly adults as well as in patients suffering from mild cognitive impairment or early Alzheimer's disease. Therefore, tES methods might be a useful intervention tool for patients suffering from memory impairment in early terms of the disease.

The present study aims at establishing a connection between the stimulation-induced changes on associative memory performance and its underlying neurophysiological parameters. tES effects and their underlying mechanisms will be compared between healthy elderly controls and clinical study populations receiving either real or sham tES over the left ventrolateral prefrontal cortex during an associative memory task.

Study Overview

• Status: Completed
• Conditions: Healthy; Alzheimer Disease; Mild Cognitive Impairment
• Intervention / Treatment: Device: real anodal transcranial direct current stimulation; Device: real transcranial alternating current stimulation; Device: sham transcranial electric current stimulation

• Study Type: Interventional
• Enrollment (Actual): 28
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Switzerland
  • Bern, Switzerland, 3000
    • University Hospital of Old Age Psychiatry and Psychotherapy

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 60 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Written informed consent
• Non-smokers
• Right-handedness
• Native German speakers or comparable level of fluency
• Normal or corrected-to-normal vision

Exclusion Criteria:

• Neurological or psychiatric condition (other than diagnosed cognitive impairment)
• Past head injuries
• Magnetizable implants
• History of seizures
• Current or life-time alcohol or drug abuse
• Skin diseases

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Real tDCS; 20 min of 2 mA real anodal transcranial direct current stimulation applied via 5x7 cm rubber electrode over the VLPFC (current density: 0.057 mA/cm2) and cathodal 10x10 rubber electrode over supraorbital region (current density: 0.02 mA/cm2). Additional ramp-up and ramp-down phase of 15 s at the beginning and the end of stimulation.	Device: real anodal transcranial direct current stimulation; The MR-compatible neuroConn DC-Stimulator MR (neuroCare Group, Ilmenau, Germany) will be used.
Experimental: Real tACS; 20 min of 2 mA real transcranial alternating current stimulation in theta frequency applied via 5x7 cm and 10x10 cm rubber electrodes over the VLPFC (current density: 0.057 mA/cm2) and supraorbital region (current density: 0.02 mA/cm2). Additional ramp-up and ramp-down phase of 15 s at the beginning and the end of stimulation.	Device: real transcranial alternating current stimulation; The MR-compatible neuroConn DC-Stimulator MR (neuroCare Group, Ilmenau, Germany) will be used.
Sham Comparator: Sham tES; 30 s of 2 mA sham transcranial electric current stimulation applied via 5x7 cm and 10x10 cm rubber electrodes over the VLPFC (current density: 0.057 mA/cm2) and supraorbital region (current density: 0.02 mA/cm2). Additional ramp-up and ramp-down phase at beginning and end of stimulation lasting for 15 s. Electrodes remain attached to the participant's head for the duration of the encoding phase of the memory task.	Device: sham transcranial electric current stimulation; The MR-compatible neuroConn DC-Stimulator MR (neuroCare Group, Ilmenau, Germany) will be used.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Performance on immediate cued recall task	Number of correct responses on retrieval task of previously learned associative memory items	20 min
Performance on delayed cued recall task	Number of correct responses on retrieval task of previously learned associative memory items	24 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
task-dependent BOLD activity	Measured with functional magnetic resonance imaging (fMRI)	20 min
resting-state BOLD activity	Measured with functional magnetic resonance imaging (fMRI)	10 min

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Performance on cued recall task	Number of correct responses on retrieval task of previously learned associative memory items	follow-up after 24 hours
Performance on recognition task	Number of correct responses on retrieval task of previously learned associative memory items	follow-up after 24 hours

Collaborators and Investigators

• Sponsor: University of Bern
• Investigators: Principal Investigator: Stefan Klöppel, Prof.Dr.med, University of Bern

Study record dates

Study Major Dates

• Study Start (Actual): April 9, 2018
• Primary Completion (Actual): September 30, 2018
• Study Completion (Actual): February 24, 2020

Study Registration Dates

• First Submitted: November 14, 2017
• First Submitted That Met QC Criteria: November 17, 2017
• First Posted (Actual): November 22, 2017

Study Record Updates

• Last Update Posted (Actual): March 13, 2020
• Last Update Submitted That Met QC Criteria: March 12, 2020
• Last Verified: March 1, 2020

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Mental Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurocognitive Disorders; Neurodegenerative Diseases; Dementia; Tauopathies; Cognition Disorders; Alzheimer Disease; Cognitive Dysfunction
• Other Study ID Numbers: 2017-01197

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No