Healthy, Mild Cognitive Impairment, Alzheimer Disease
Conditions
Brief summary
With aging the amount of slow wave sleep decreases drastically and this disruption is markedly exaggerated in older adults suffering from mild cognitive impairment and Alzheimer's disease. Critically, the disruption of slow wave sleep and cognitive decline seem bidirectionally linked forming a vicious cycle. In the long run, improving slow wave sleep might be a useful intervention tool to delay the onset of cognitive decline. The present study aims at improving slow wave sleep and memory functions through a closed-loop acoustic stimulation approach. A closed-loop algorithm is used that detects slow waves in the electroencephalogram and is programmed to present short tones (50 ms) in the rhythm of these waves. This procedure has shown to boost both slow wave sleep as well as memory performance, mainly in young adults and when applied for one night. Here, the investigators apply tones via multiple consecutive nights and assess memory performance during this 3-night intervention.
Interventions
OTHERClosed loop acoustic stimulation
The intervention consists of three consecutive nights of closed loop acoustic stimulation during slow wave sleep. An established closed-loop algorithm is utilized that detects slow oscillations in the electroencephalogram and is programmed to present short tones (50 ms) into their up-states. Tones will be presented via a headband with integrated speakers. The procedure does not wake participants
Sham acoustic stimulation: participants wear the headband but no stimuli are delivered during slow wave sleep. This ensures that in both the control and the intervention group the conscious experiences are the same.
Sponsors
University of Bern
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
60 Years to 85 Years
Healthy volunteers
Yes
Inclusion criteria
* Written informed consent * Fluent in German * Normal or corrected to normal vision * Unimpaired hearing * For healthy group: Montreal Cognitive Assessment Score ≥ 26 * For MCI group: Montreal Cognitive Assessment Score \< 26 * For at risk group: smoker, high cholesterol, high blood pressure and high fasting plasma glucose OR smoker, high BMI, physically inactive, unhealthy dietary habits
Exclusion criteria
* Known sleep problems such as Insomnia, restless leg syndrome, apnea * Irregular sleep pattern * Symptoms of depression * History of untreated severe neurological and psychiatric diseases * Alcohol or substance abuse * Use of medication acting on the central nervous system
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change from baseline episodic memory performance after three nights of intervention | The change in memory performance will be assessed between the baseline measurement (evening before the first intervention night) and on the morning of the last intervention night (1 hour after waking), 3 days after initial encoding | Face-occupation associative memory task: encoding of 40 faces coupled with 40 occupations takes place on the evening of the first intervention night followed by a retrieval session (BASELINE). Feedback-based retrieval sessions take place on the following mornings and evenings of three consecutive intervention nights (4 feedback-based encoding sessions). After the last intervention night a retrieval session without feedback is performed upon waking (ASSESSMENT OF CHANGE) |
| Change from baseline performance in computer-based verbal new learning task (episodic memory) after three nights of intervention | The change in new learning performance will be assessed between the baseline measurement (morning before the first intervention night) and on the morning of the last intervention night (1.5 hour after waking), 3 days after. | Verbal associative memory task: a list of 30 moderately associated word pairs (e.g. balloon-air) are presented on a screen. The respective word pairs are displayed for five seconds each and participants are asked to memorize them. After a one-minute break, a cued recall follows in which one word of each pair is randomly shown and participants are prompted to name the matching second word (BASELINE). After the last intervention night a different list of 30 word pairs is used for another session of encoding and retrieval (ASSESSMENT OF CHANGE) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Improvement in episodic memory performance at follow-ups | One week as well as 3 months after intervention | Face-occupation associative memory task |
| Improvements in sleep physiology | Three consecutive nights of EEG measurement/polysomnography | EEG-data: Quality of slow wave sleep, number of slow oscillations, number of sleep spindles can all be measured by the data provided by the electroencephalographic recordings. A high densitiy electrode cap with 128 channels is used for this purpose. |
| Improvement in new learning of episodic memory at follow-ups | One week as well as 3 months after intervention | Verbal associative memory task |
| Decreases in plasma amyloid-beta | Blood samples will be taken twice: on the morning before the first intervention night, on the morning after the last intervention night (3 days apart) | — |
Other
| Measure | Time frame | Description |
|---|---|---|
| General cognitive functions: cognitive flexibility | Assessed four times: on the morning before the first intervention night, on the morning after the last intervention night, one week after and 3 months after the intervention | A computer based task switch task is performed (established task for cognitive flexibility) |
| General cognitive functions: working memory | Assessed four times: on the morning before the first intervention night, on the morning after the last intervention night, one week after and 3 months after the intervention | A computer based visual n-back task is performed (established task for working memory) |
| General cognitive functions: cognitive inhibition | Assessed four times: on the morning before the first intervention night, on the morning after the last intervention night, one week after and 3 months after the intervention | A computer based go/no go task is performed (established task for cognitive inhibition) |
Countries
Switzerland
Outcome results
None listed