This study aims to evaluate the effects of endogenous gamma non-flickering light stimulation on resting-state EEG rhythms and cognitive function in cognitively healthy older adults. Specifically, it will assess the immediate and long-term effects of this stimulation on brainwave activity and cognitive performance. The study will explore the potential of gamma light stimulation as a non-pharmacological intervention for cognitive decline in aging populations.
Some Alzheimer's disease (AD) studies have investigated the effects of gamma-frequency light stimulation on healthy older adults and AD patients; they have several limitations, including small sample sizes, short intervention durations, the use of flickering light (which may cause discomfort), and lack of rigorous randomized controlled trials. The aim of this study is to address these gaps by conducting a randomized, placebo-controlled, double-blind trial. This study will recruit 52 cognitively healthy older adults aged 55 and above (N= 52). Participants will be randomly assigned to either the experimental group (N=26), receiving endogenous gamma non-flickering light stimulation, or the control sham group (N=26), receiving 70 Hz non-flickering light stimulation. The intervention will consist of 1 hour of daily stimulation, 7 days a week, for a total of 4 weeks (28 hours). Both participants and outcomes assessors will remain blinded to group allocation. Resting-state EEG and cognitive assessments will be conducted at three time points: prior to the intervention (T1), post one-hour intervention (T2), and post one-month intervention (T3). Resting-state brainwave activity will be the primary outcome, with data collected at all three time points (T1, T2, and T3). As secondary outcomes, cognitive assessments will be administered at T1 and T3. Adverse events will also be recorded by participants immediately following each light stimulation session. The primary aim of this study is to assess the immediate (T2 relative to T1) and long-term (T3 relative to T1) effects of endogenous gamma light stimulation on resting-state brainwave activity. Secondary objectives include evaluating cognitive performance and assessing the safety, user acceptance, and adherence to the intervention device. The results of this study will provide valuable insights into the potential of endogenous gamma light stimulation as a non-pharmacological intervention for cognitive decline in aging populations.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
52
Participants will receive light stimulation using the Gamma Wave Stimulation Table Lamp (Aleddra, Inc., USA) for 1 hour per day, 7 days a week, over 4 weeks, for a total of 28 hours.
Chang Gung University
Taoyuan District, Guishan, Taiwan
RECRUITINGChanges in gamma brain oscillations.
Gamma (31-100Hz) brain oscillations obtained through resting-state EEG will evaluate the changes of gamma light stimulation intervention.
Time frame: baseline (T1), post one-hour intervention (T2), post one-month intervention (T3)
Change score of the Cognitive Abilities Screening Instrument (CASI).
CASI will be applied to measure the participant's general cognitive ability. The range of score is 0 to 100, with a higher score indicating better performance.
Time frame: baseline (T1), post one-month intervention (T3)
Change score of the Chinese version Verbal Learning Test (CVVLT).
A nine-item of CVVLT (total recall, delayed recall) will be applied to measure the participant's memory ability, with a higher score indicating better performance.
Time frame: baseline (T1), post one-month intervention (T3)
Change score of the WMS-III logical memory test
WMS-III logical memory test (immediate recall, delayed recall) will be applied to measure the participant's memory ability. The maximum score is 25 for each recall trial, with a higher score indicating better performance
Time frame: baseline (T1), post one-month intervention (T3)
Change score of the Taylor Complex Figure Test (TCFT).
TCFT (immediate recall, delayed recall) will be applied to measure the participant's memory ability. The maximum score is 36 for each recall trial, with a higher score indicating better performance.
Time frame: baseline (T1), post one-month intervention (T3)
Performance changes of the Trail Making Test Form A/B (TMT-A/B).
TMT-A/B will be applied to measure participant's attention and executive function. The number of seconds to complete each trial and the number of errors would be recorded, with a higher value indicating greater impairment.
Time frame: baseline (T1), post one-month intervention (T3)
Subjective cognition decline complaint survey.
A 14-item Subjective Memory Complaints Questionnaire measured memory impairment. The response was restricted to either "Yes" or "No".
Time frame: baseline (T1), post one-month intervention (T3)
Change score of the category Verbal Fluency Test (VFT).
The category VFT will be applied to measure the participant's language and executive function, with a higher score indicates better performance.
Time frame: baseline (T1), post one-month intervention (T3)
Safety/Adverse event outcome measure.
Adverse events, such as fatigue, headache, dizziness, dazzling, ocular pain, and others, will be recorded using a 6-point Likert scale ranging from 'not at all' to 'extremely uncomfortable' (0 = not at all, 1 = minimal discomfort, 2 = mild discomfort, 3 = tolerable, 4 = severe discomfort, 5 = extreme discomfort). Participants will report adverse events (such as fatigue, headache, dizziness, dazzling, ocular pain, and others) using a 6-point Likert scale ranging from 'not at all' to 'extremely uncomfortable' after each light stimulation session.
Time frame: Throughout the one-month intervention
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