Supporting Episodic Memory With Transcranial Direct Current Stimulation in Healthy Controls and Dementia Patients

Not Applicable

Terminated

• Conditions: Mild Cognitive Impairment; Alzheimer Disease; Healthy
• Interventions: Device: real anodal transcranial direct current stimulation (tDCS); Device: sham transcranial direct current stimulation (tDCS)

• Registration Number: NCT03227185
• Lead Sponsor: University of Bern

Brief Summary

Previous studies showed that anodal tDCS applied over the dorsolateral prefrontal cortex (DLPFC) improved episodic memory performance, indicating a possible use as an intervention for patients suffering from memory impairments. At the same time, only scant evidence (provided by functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy (MRS)) exists regarding the underlying mechanisms, thus hindering a more targeted application.

The present study aims at establishing a connection between the stimulation-induced change in episodic memory performance on the behavioural level and neurophysiological parameters. TDCS effects and the underlying mechanisms will be compared between different study conditions, receiving either real anodal tDCS or sham stimulation over the left dorsolateral prefrontal cortex during an episodic memory task.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2017-07-19
• Study First Submitted QC: 2017-07-21
• Study First Posted: 2017-07-24
• Study Start: 2017-10-01
• Primary Completion: 2019-10-18
• Study Completion: 2019-10-19
• Status Verified: 2020-02
• Last Update Submitted: 2020-02-25
• Last Update Posted: 2020-02-28

Recruitment & Eligibility

• Status: TERMINATED
• Sex: All
• Target Recruitment: 55

Inclusion Criteria

• Written informed consent
• Right-handedness
• Non-smokers
• 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
• Pregnancy
• Skin diseases

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Real - sham anodal tDCS	sham transcranial direct current stimulation (tDCS)	Session 1: 20 min of 1 mA anodal tDCS applied via 5x7 cm rubber electrodes over the DLPFC (current density: 0.028 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. Session 2: 30 s of 1 mA anodal tDCS applied via 5x7 cm rubber electrodes over the DLPFC (current density: 0.028 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.
Sham - real anodal tDCS	real anodal transcranial direct current stimulation (tDCS)	Session 1: 30 s of 1 mA anodal tDCS applied via 5x7 cm rubber electrodes over the DLPFC (current density: 0.028 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. Session 2: 20 min of 1 mA anodal tDCS applied via 5x7 cm rubber electrodes over the DLPFC (current density: 0.028 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.
Sham - real anodal tDCS	sham transcranial direct current stimulation (tDCS)	Session 1: 30 s of 1 mA anodal tDCS applied via 5x7 cm rubber electrodes over the DLPFC (current density: 0.028 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. Session 2: 20 min of 1 mA anodal tDCS applied via 5x7 cm rubber electrodes over the DLPFC (current density: 0.028 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.
Real - sham anodal tDCS	real anodal transcranial direct current stimulation (tDCS)	Session 1: 20 min of 1 mA anodal tDCS applied via 5x7 cm rubber electrodes over the DLPFC (current density: 0.028 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. Session 2: 30 s of 1 mA anodal tDCS applied via 5x7 cm rubber electrodes over the DLPFC (current density: 0.028 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.

Primary Outcome Measures

Name	Time	Method
Episodic memory performance - delayed recall 1	20 min after encoding phase	Number of remembered words in the delayed recall after a short delay at the day of the on-site visit
Episodic memory performance - learning curve	0.25 hours	Number of encoded words during the three consecutive immediate retrievals in the encoding phase
Episodic memory performance - delayed recall 2	1 day after on-site visit	Number of remembered words one day after learning

Secondary Outcome Measures

Name	Time	Method
Neurotransmitter levels	0.5 hours	Changes in neurotransmitter levels (gamma-Aminobutyric acid (GABA) and glutamatergic metabolites (Glx) due to tDCS (comparing pre- and post-stimulation measurements in DLPFC)

Trial Locations

Locations (1)

University Hospital of Old Age Psychiatry and Psychotherapy; 🇨🇭 Bern, Switzerland