Effects of Brain Stimulation During a Daytime Nap on Memory Consolidation in Older Adults

Study Overview
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Brief Summary
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The beneficial effect of nocturnal as well as daytime sleep on memory consolidation is well-documented in young, healthy subjects. Slow wave sleep (SWS), in particular, with its slow oscillating activity have shown to enhance declarative, hippocampus-dependent memory representations. This impact of sleep on memory performance can be additionally enhanced by exogeneous induction of transcranial slow oscillating stimulation (tSOS) within the frequency range of SWS in humans (0,7- 0,8 Hz) during sleep, as has been demonstrated in young, healthy subjects. If older adults that commonly experiencing cognitive decline, including long-term retention of declarative memory - benefit from transcranial slow oscillatory stimulation (tSOS) during sleep in the same way has not been studied so far. The primary goal of the study is therefore to investigate the impact of oscillating current stimulation (tSOS) during a daytime nap on declarative memory consolidation in older adults.

Official Title
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Impact of Transcranial Slow Oscillating Stimulation on Memory Consolidation During Slow Wave Sleep in Older Adults

Conditions
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Older Adults (50-90 Years)

Intervention / Treatment
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* Device: brain stimulation
* Device: Sham Stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age: 50-90 years right handed inobtrusive neuropsychological examination Exclusion Criteria: untreated severe internal or psychiatric diseases epilepsy other severe neurological diseases eg., previous major stroke, brain tumour dementia contraindications to MRI

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 0,75 Hz stimulation<br>transcranial slow oscilliating stimulation (tSOS)during periods of SWS | Device: brain stimulation<br> <br> * Other names: oscillating direct current brain stimulation;|
| Sham Comparator: no stimulation<br>Sham stimulation during periods of SWS | Device: Sham Stimulation<br> <br> * Other names: no stimulation;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Retention of declarative memories after 0.75 Hz stimulation during SWS, vs after sham stimulation during SWS | Retention between stimulation conditions (0.75 Hz during SWS, vs sham stimulation during SWS) in the declarative memory task. | 4 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 1. Amount of Slow wave Sleep | 1. Amount of slow wave sleep assessed by standard polysomnographic criteria in 0,75 Hz vs SHAM stimulation during SWS. | 4 weeks | 
| 2. sleep spindels | 2.Spindel activity during sleep indicated via several spindel parameters like number, duration, frequency of spindles; compared between 0,75 Hz and SHAM stimulation during SWS. | 4 weeks | 
| 3. EEG-correlates | 3. Neuronal correlates (EEG-power in slow oscillation frequency bands induced by 0,75 Hz vs SHAM stimulation during SWS; EEG-correlates of encoding and retrieval of a declarative memory task). | 4 weeks | 
| 4. further memory systems | 4. Performance in further memory systems (procedural), compared between 0,75 Hz and SHAM stimulation during SWS. | 4 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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aging, cognitive decline, brain stimulation, tSOS, tDCS, sleep, nap, daytime sleep, memory, memory consolidation