Alzheimer's disease (AD) is characterized by significant memory loss, toxic protein deposits amyloid and tau) in the brain, and changes in the gamma frequency band on EEG. Gamma waves are important for memory, and in patients with AD, there are fewer gamma waves in the brain. The investigator's lab found that boosting gamma waves in AD mouse models using light and sound stimulation at 40Hz not only reduced amyloid and tau in the brain, but also improved memory. The investigators developed a light and sound device for humans that stimulates the brain at 40Hz that can be used safely at home. The investigators also developed a vibrating device for humans that stimulates the brain at 40Hz via tactile stimulation. The investigators want to see if using these devices can prevent dementia in people who are at risk for developing Alzheimer's disease.
The investigators are recruiting 60 participants who have been diagnosed with Alzheimer's disease to participate in this study. There will be a small cohort of 4 early-onset AD participants aged 50-65, and the rest will be diagnosed with typical AD and aged 65+. It will take place at the Massachusetts Institute of Technology in Cambridge, MA, and will last 6 months with 3 required visits to the institution: the first at baseline, the second at three months, and the last after six months. Visits will include blood tests, fecal samples, EEG (using light, sound, and tactile stimulation), MRI, memory and cognitive tests, and questionnaires to monitor progress. Participants will take home a gamma light and sound device to use daily as well as a "Fitbit" type of watch to wear to track sleep patterns. Half of the participants will receive sham treatment, meaning they will use the investigators' device but the light and sound will not be set at 40Hz. The other half will receive the same device but it will be set to stimulate the brain with 40Hz light and sound. Neither the participant nor the investigators will know whether the participant is receiving sham or active stimulation. Participants will use the device for six months at home, for 60 minutes each day when they are awake. After six months, participants will have the option of continuing in the study for at least one year, during which time they will be guaranteed the 40Hz active treatment, regardless of their original group assignment. During this time, participants will continue to use the device for 60 minutes every day, and they will come in for visits to MIT at yearly time points.
The purpose of this study is to determine whether gamma entrainment through non-invasive 40Hz sensory stimulation is possible in those with AD, and whether functional connectivity in their brain and molecular biomarkers of AD will change after 6 months of daily treatment with the investigators' light and sound device. The treatment's impact on the microbiome, cognition, and daily sleep and activity will also be measured. This study will provide critical insight into extended therapy involving non-invasive 40Hz sensory stimulation as a possible therapeutic strategy for mild to moderate Alzheimer's disease.
