Alzheimer Disease, Healthy, Mild Cognitive Impairment
Conditions
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.
Interventions
DEVICEreal anodal transcranial direct current stimulation (tDCS)
The MR-compatible neuroConn DC-Stimulator MR (neuroCare Group, Ilmenau, Germany) will be used in the study.
DEVICEsham transcranial direct current stimulation (tDCS)
The MR-compatible neuroConn DC-Stimulator MR (neuroCare Group, Ilmenau, Germany) will be used in the study.
Sponsors
University of Bern
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Intervention model description
Participants will be randomly assigned to two possible sequences of stimulation conditions. Group 1 will receive real tDCS stimulation to the left dlPFC during encoding on the first day and sham stimulation on the second day, and group 2 will receive sham stimulation during encoding on the first day and real tDCS on the second day. The participants will be randomized with equal probability to each of the two groups, using block randomization..
Eligibility
Sex/Gender
ALL
Age
20 Years to 85 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 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 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 - delayed recall 2 | 1 day after on-site visit | Number of remembered words one day after learning |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| 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) |
Countries
Switzerland
Outcome results
None listed