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

Development and Validation of an Innovative Gamma Auditory Stimulation System for Older Adults With Cognitive Decline: A Randomized, Double-blind, Placebo-controlled Study (Study 1)

Animal studies have shown that 40 Hz auditory stimulation alone can improve spatial memory and reduce Aβ deposition. However, human studies using 40 Hz auditory stimulation alone remain limited. Therefore, this study will use a randomized, double-blind, placebo-controlled design to investigate the effects of 40 Hz auditory stimulation on cognitive function, EEG activity, sleep quality, and quality of life in older adults with mild cognitive impairment (MCI) or mild dementia.

Amyloid-beta (Aβ) aggregation and hyperphosphorylated tau protein tangles are widely recognized as the main pathological features of Alzheimer's disease (AD). Numerous domestic and international studies have demonstrated that 40 Hz gamma visual stimulation can effectively enhance 40 Hz gamma neural oscillations in healthy adults and older adults, improve cognitive performance and memory function in older adults and individuals with AD, and has shown good safety with no severe adverse effects.

Nevertheless, there are still several limitations to using 40 Hz visual stimulation as an intervention. Extended exposure to light sources may cause discomfort, affecting participants' willingness to continue. Prolonged light exposure may also increase the risk of seizures in photosensitive individuals. In addition, participants are required to actively fixate on the light source, which may reduce intervention adherence. Most importantly, the ecological validity of light-based stimulation remains low. Many studies require participants to gaze at light for at least five minutes or more, and daily sessions of up to an hour over several months are challenging to implement in daily life. To address these limitations, this project proposes using 40 Hz auditory stimulation as a more practical and sustainable intervention.

Moreover, animal studies have confirmed that 40 Hz auditory stimulation alone can improve spatial memory and reduce Aβ deposition. However, evidence on the independent application of 40 Hz auditory stimulation in humans remains limited. Therefore, this project will adopt a randomized, double-blind, placebo-controlled design to investigate the effects of 40 Hz auditory stimulation on cognitive function, EEG activity, sleep quality, and quality of life in older adults with mild cognitive impairment (MCI) or mild dementia.

Inclusion Criteria:

1. Age over 60 years old.
2. MMSE≤ 24
3. CDR scores of 0.5 and 1
4. Voluntary to sign the Informed Consent Form.

Exclusion Criteria:

1. Diagnosis of other psychiatric or neurological disorders
2. Drug or alcohol addictions.
3. Serious heart, liver or kidney disorders, and visual, auditory or motor impairments interfering with neuropsychological tests.
4. History of clinical stroke, major depressive disorder or dysthymic disorder according to the DSM-5.