Modulating Prospective Memory in Older Adults With Non-invasive Brain Stimulation

Modulating Prospective Memory in Older Adults With Noninvasive Brain Stimulation

Prospective memory is the ability to remember to carry out intentions with a certain delay (e.g. remember to buy stamps when passing a postal office). Prospective memory tasks require a large degree of self-initiated retrieval and in the absence of a prompt to recall, people must 'remember to remember' by their own volition. Thus, prospective memory is a challenge - especially in old age with increasing health-related prospective memory demands.

Previous studies reported links between neural activity in specific brain regions and prospective memory performance. Yet, the mere occurrence of a change in brain activity in concomitance with performance of a behavioral task is not sufficient to confirm a causal relationship between the two phenomena. Therefore, this study aims to apply non-invasive brain stimulation to facilitate or inhibit activity in different brain regions presumed to be functionally associated with prospective memory. Additional to the prospective memory tasks, the investigators will implement control tasks (i.e., attention) to assess whether stimulation will specifically enhance prospective memory performance or whether other cognitive functions will be modulated additionally.

It is hypothesized that stimulation will lead to changes in prospective memory functioning. Further, the investigators expect that facilitation of attentional processes might be linked to prospective memory improvements.

Study Overview

• Status: Completed
• Conditions: Healthy Aging
• Intervention / Treatment: Device: Non-invasive brain stimulation; Device: Sham stimulation

Detailed Description

This study aims to modulate neural activity in the left and right inferior frontal lobe as well as in the right superior parietal lobe via high-definition transcranial direct current stimulation (HD-tDCS) in older adults. There is evidence from functional magnetic resonance imaging (fMRI) studies that these areas are involved in prospective memory performance in younger and older adults but a causal relation between activity in these areas and responses in prospective memory tasks has not been established so far.

A double blind, sham-controlled, parallel group design will be applied. Healthy older adults (n=105) will participate in two separate sessions: During the first baseline session, no stimulation is applied. For the second session, participants will then be randomly assigned to one of seven experimental groups (cathodal vs. anodal right inferior frontal lobe (rIFL); cathodal vs. anodal left inferior frontal lobe (lIFL); cathodal vs. anodal right superior parietal lobe (rSPL); or sham). Real stimulation will be applied during 20 minutes with one Milliamp (mA). In case of sham stimulation (i.e., control intervention), the electrode positions and the attachment procedures correspond to those of real tDCS but the electrical current will only be ramped up to one mA and switched off completely after 30 s of stimulation.

The primary objective of this study is the modulation of prospective memory performance in a computer-based task via tDCS. Further, this study aims to clarify the role of attentional control for prospective memory performance, as both processes seem to recruit similar neural structures. Additionally, naturalistic and self-rated prospective memory performance will be assessed.

It is hypothesized that stimulation of the right inferior frontal lobe will lead to changes in prospective memory performance and attentional processes. Whether cathodal or anodal stimulation will enhance performance is not clear yet, since previous fMRI studies were inconsistent about activity changes in older adults. Further, the investigators expect that anodal stimulation of the left inferior frontal cortex may lead to faster responses to prospective memory stimuli, whereas cathodal stimulation of the same area may lead to prolonged reaction times. It is hypothesized that attentional control will not be affected by stimulation of the left inferior frontal lobe. Finally, the investigators expect that anodal stimulation of the right superior parietal cortex will lead to better prospective memory and attentional control performance, whereas cathodal stimulation will have detrimental effects on both functions.

• Study Type: Interventional
• Enrollment (Actual): 106
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Switzerland
  • Bern, Switzerland, 3008
    • Universitätsklinik für Alterspsychiatrie und Psychotherapie

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 60 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• No cognitive impairments
• Fluent in German
• Right-handed
• Normal or corrected-to-normal vision
• Non-smokers
• Written informed consent

Exclusion Criteria:

• Current/lifetime severe psychiatric or neurological disorder
• Metal implants in the head area
• Psychotropic medication
• Dermatosis
• Current/lifetime alcohol abuse
• Magnetisable implants

Study Plan

How is the study designed?

Design Details

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

Number of Arms

7

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: anodal stimulation of the rIFL; Anodal stimulation over the right inferior frontal lobe	Device: Non-invasive brain stimulation; Stimulation will be applied once per subject with one mA for 20 minutes over either the left inferior frontal lobe, the right inferior frontal lobe or the right superior parietal lobe.; Other Names: high-definition transcranial direct current stimulation; HD-tDCS; Soterix medical
Experimental: cathodal stimulation of the rIFL; Cathodal stimulation over the right inferior frontal lobe	Device: Non-invasive brain stimulation; Stimulation will be applied once per subject with one mA for 20 minutes over either the left inferior frontal lobe, the right inferior frontal lobe or the right superior parietal lobe.; Other Names: high-definition transcranial direct current stimulation; HD-tDCS; Soterix medical
Experimental: anodal stimulation of the lIFL; Anodal stimulation over the left inferior frontal lobe	Device: Non-invasive brain stimulation; Stimulation will be applied once per subject with one mA for 20 minutes over either the left inferior frontal lobe, the right inferior frontal lobe or the right superior parietal lobe.; Other Names: high-definition transcranial direct current stimulation; HD-tDCS; Soterix medical
Experimental: cathodal stimulation of the lIFL; Cathodal stimulation over the left inferior frontal lobe	Device: Non-invasive brain stimulation; Stimulation will be applied once per subject with one mA for 20 minutes over either the left inferior frontal lobe, the right inferior frontal lobe or the right superior parietal lobe.; Other Names: high-definition transcranial direct current stimulation; HD-tDCS; Soterix medical
Experimental: anodal stimulation of the rSPL; Anodal stimulation over the right superior parietal lobe	Device: Non-invasive brain stimulation; Stimulation will be applied once per subject with one mA for 20 minutes over either the left inferior frontal lobe, the right inferior frontal lobe or the right superior parietal lobe.; Other Names: high-definition transcranial direct current stimulation; HD-tDCS; Soterix medical
Experimental: cathodal stimulation of the rSPL; Cathodal stimulation over the right superior parietal lobe	Device: Non-invasive brain stimulation; Stimulation will be applied once per subject with one mA for 20 minutes over either the left inferior frontal lobe, the right inferior frontal lobe or the right superior parietal lobe.; Other Names: high-definition transcranial direct current stimulation; HD-tDCS; Soterix medical
Sham Comparator: sham stimulation; Sham stimulation over either of the three real stimulation areas	Device: Sham stimulation; The electrode positions and the attachment procedures correspond to those of real tDCS but the electrical current will only be ramped up to 1 mA and switched off completely after 30 s of stimulation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Prospective memory performance	Assessed with a computer task. Number of correct answers given to prospective memory stimuli. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: during intervention), fixed to 14 minutes
Prospective memory reaction time	Assessed with a computer task. Reaction times of answers given to prospective memory stimuli. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: during intervention), fixed to 14 minutes
Executive controlling functioning	Assessed with a computer task (ANT - Attentional Network Task). Interference between answers given to congruent and incongruent stimuli. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: during intervention), task fixed to 6 minutes
Inhibition errors	Assessed with a computer task (Test of Attentional Performance). Sum of incorrect responses to no-go stimuli. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: directly after intervention), 2 minutes
Divided attention reaction time	Assessed with a computer-based task (Test of Attentional Performance). Median reaction time of correct answers. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: directly after stimulation), 3 minutes 30 seconds
Flexibility performance	Assessed with a computer task (TAP- Test of Attentional Performance). Number of correct answers. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: directly after intervention), 3 minutes
Divided attention misses	Assessed with a computer task (TAP - Test of Attentional Performance). Sum of missed target stimuli. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: directly after intervention), 3 minutes 30 seconds
Flexibility reaction-time	Assessed with a computer task (TAP - Test of Attentional Performance). Mean/ median of reactions times of correct responses. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: directly after intervention), 3 minutes
Inhibition reaction time	Assessed with a go/no-go computer task (TAP -Test of Attentional Performance). Mean/ median of reactions times to correct responses. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: directly after intervention), 2 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Alerting network functioning	Assessed with a computer task (ANT - Attentional Network Task). Contrasting reaction times of answers given to stimuli with alerting cues to those without alerting cues. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: during intervention), task fixed to 6 minutes
Orienting network functioning	Assessed with a computer task (ANT - Attentional Network Task). Contrasting reaction times of answers given to stimuli with reliable spatial cues to those without spatial cues. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: during intervention), task fixed to 6 minutes
Ongoing-task performance	Assessed with a computer task. Number of correctly answered ongoing task stimuli in the course of the prospective memory task. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: during intervention), fixed to 14 minutes
Ongoing-task reaction time	Assessed with a computer task. Mean/median response time of correct ongoing task answers in the course of the prospective memory task. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: during intervention), fixed to 14 minutes
Ongoing-task intra-individual coefficient of variation	Assessed with a computer task. Variability of response times (i.e., within-person fluctuation in response latency) to ongoing task stimuli in the course of the prospective memory task. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: during intervention), fixed to 14 minutes

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Self-rated prospective memory	Assessed with a questionnaire (PRMQ - Prospective Retrospective Memory Questionnaire). Comparison to performance in other tasks.	Only at baseline session, after computer-based tasks, 10 minutes
Self-rated metacognitive prospective memory	Assessed with a questionnaire (MPMI - Metacognitive Prospective Memory Inventory). Comparison to performance in other tasks.	Only at stimulation session, after intervention, 10 minutes
Stimulation Side-Effects	Self-rating about adverse side effects during and after stimulation are assessed with a questionnaire.	Only at stimulation session, after intervention, 3 minutes
Naturalistic prospective memory	Assessed with a behavioral task. Number of correctly retrieved naturalistic prospective memory intentions. Change from baseline to intervention session, difference between intervention groups.	5 minutes per session; retrieval within five days after each session
Inhibition intra-individual coefficient of variation	Assessed with a go/no-go computer task (TAP -Test of Attentional Performance). Variability of response times (i.e., within-person fluctuation in response latency) to go-stimuli. Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: directly after intervention), 2 minutes
Flexibility intra-individual coefficient of variation	Assessed with flexibility computer task (TAP -Test of Attentional Performance). Variability of response times (i.e., within-person fluctuation in response latency). Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: directly after intervention), 3 minutes
Divided attention intra-individual coefficient of variation	Assessed with a computer-based task (Test of Attentional Performance). Variability of response times (i.e., within-person fluctuation in response latency). Change from baseline to intervention session, difference between intervention groups.	During both sessions (for stimulation session: directly after stimulation), 3 minutes 30 seconds

Collaborators and Investigators

• Sponsor: University of Bern
• Investigators: Study Chair: Jessica Peter, PD Dr., University of Bern; Study Chair: Matthias Kliegel, Prof. Dr., University of Geneva; Study Chair: Nadine Schmidt, MSc., University of Bern; Principal Investigator: Stefan Klöppel, Prof. Dr., University of Bern

Study record dates

Study Major Dates

• Study Start (Actual): June 28, 2021
• Primary Completion (Actual): October 31, 2023
• Study Completion (Actual): October 31, 2023

Study Registration Dates

• First Submitted: May 6, 2021
• First Submitted That Met QC Criteria: May 6, 2021
• First Posted (Actual): May 12, 2021

Study Record Updates

• Last Update Posted (Estimated): December 12, 2023
• Last Update Submitted That Met QC Criteria: December 11, 2023
• Last Verified: December 1, 2023

More Information

Terms related to this study

• Other Study ID Numbers: 2019-01599

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