Efficacy of Gamma Auditory Stimulation for Cognitive Decline in Older Adults (Study 1)

The changes of power spectral density (PSD) and functional connectivity (FC) at each frequency band will be analyzed by EEG data from each subject.

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.

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

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

A neuropsychological test used to assess cognitive impairment, particularly in the context of Alzheimer's disease. The ADAS-Cog typically has a total score ranging from 0 to 70, with higher scores indicating greater cognitive impairment.

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.

The category VFT will be applied to measure the participant's language and executive function, with a higher score indicates better performance.

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.

This is a widely used neuropsychological assessment that measures attention (Digit Span Forward), and working memory (Digit Span Backward). If the participant correctly repeats the digit sequence, the number of digits in the next sequence will increase. The test will be terminated after a set number of errors.

It evaluates 12 neuropsychiatric domains. For each symptom, the NPI assesses both its frequency (how often it occurs) and severity (how intense it is). A higher score indicates more severe symptom.

This tool consists of 15 yes-or-no questions and is commonly used to assess depression in older adults. A higher score indicates more severe depression.

It used to comprehensively assess participants' sleep quality over the past month with 19 questions. Each component is scored from 0 to 3, with higher scores indicating greater sleep problems. The total PSQI score, a sum of all component scores, will range from 0 to 21, where a score above 5 indicates poor sleep quality.

It used to assess an individual's quality of life with five questions and each dimension has five levels of severity. Additionally, the EQ-5D-5L includes a Visual Analog Scale, where respondents rate their overall health on a scale from 0 (the worst imaginable health) to 100 (the best imaginable health).

Adverse events, such as fatigue, headache, dizziness, dazzling, ear 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.

Participants will answer a device feasibility questionnaire, include "how is the usability of the device", "How is your satisfaction of the user interface " ...etc. We will use a 6-point Likert scale ranging from 'not at all' to 'extremely good'.