Claim reviewed: 40 Hz sound (and light) stimulation protects cognition and slows the progression of Alzheimer's disease.
What do we know?
40 Hz stimulation is studied in Alzheimer's research because of animal findings; human studies have used light, sound or both. A meta-analysis of 11 controlled studies found no significant change in cognitive function, and tinnitus was reported more often with stimulation. A review of 62 sound-only studies found that brain findings from animal models were not consistently replicated in humans; some studies reported positive changes in cognitive measures.
What don't we know?
The large sham-controlled HOPE study (673 participants) completed on 17 August 2026 (primary completion 22 June 2026); as of 3 October 2026 no results are posted or published. The effect of 40 Hz binaural beats heard through headphones on attention is also inconsistent: one study found none, a small one found better general attention. In the earlier OVERTURE trial (76 people, 6 months), the light-and-sound device did not separate from sham on the primary clinical measure; most authors work for the company that makes it.
Wording we use in the app: 40 Hz is a gamma rhythm studied with light-and-sound devices. This session is not a treatment.
Sources (7)
Ang ve ark. 2025 · Meta-analysis · 11 studies · 341 participants
A meta-analysis of 11 controlled studies in 341 people over 50 with Alzheimer's disease or mild cognitive impairment: 40 Hz light-and-sound stimulation did not significantly change cognitive function or daily activities, though some brain-structure measures changed. Tinnitus was reported more often with stimulation (2 studies).
Cognitive function SMD 0.16 (95% CI −0.36 to 0.68; not significant); tinnitus risk difference 0.16 (p = 0.01; 2 studies)
Ang S, Zhang X, Hong J, Xue K, Li J, Du X, et al. The safety and efficacy of gamma frequency auditory and visual stimulation in the treatment of alzheimer's disease: a systematic review and meta-analysis. Transl Psychiatry. 2025;15(1):523. doi:10.1038/s41398-025-03788-4 PMID 41381439 Go to source
Bolland ve ark. 2026 · Systematic review · 62 studies · 2,179 participants
The review covered 62 studies (2,179 participants) of sound-only gamma stimulation in healthy and cognitively declining groups. Some reported positive changes in cognition and brain measures, but animal findings were not consistently replicated in humans, EEG responses did not predict cognitive effects and methods varied widely.
No pooled effect (qualitative synthesis)
First published online in 2025.
Bolland E, De Burca A, Wang SH, Khalil A, McLoughlin G. Efficacy of auditory gamma stimulation for cognitive decline: a systematic review of individual and group differences across cognitively impaired and healthy populations. NPJ Aging. 2026;12(1):8. doi:10.1038/s41514-025-00305-1 PMID 41350292 Go to source
Chan ve ark. 2025 · Pilot study · 5 participants
Five people with mild Alzheimer's disease received 1 hour of daily 40 Hz light-and-sound stimulation for two years, with no adverse events. In 3 late-onset patients, decline on cognitive measures was slower than in comparison groups drawn from external registries. The authors describe it as a small pilot supporting further research.
Chan D, de Weck G, Jackson BL, Suk HJ, Milman NP, Kitchener E, et al. Gamma sensory stimulation in mild Alzheimer's dementia: An open-label extension study. Alzheimers Dement. 2025;21(10):e70792. doi:10.1002/alz.70792 PMID 41137616 Go to source
Cognito Therapeutics 2022 · Clinical trial registration · 673 participants
A randomized, quadruple-blind study comparing 12 months of daily 60-minute gamma sensory stimulation (visual and audio per the registration; the 40 Hz detail is a company statement) with a sham device in Alzheimer's disease. With 673 participants, primary completion was 22 June 2026 and completion 17 August 2026; no results are posted in the registry (last update 9 September 2026) and none had been published as of 3 October 2026.
Cognito Therapeutics. A Randomized, Double-blind, Sham-controlled Pivotal Study of Sensory Stimulation in Subjects With Alzheimer's Disease (HOPE Study). ClinicalTrials.gov; 2022. ClinicalTrials.gov NCT05637801 Go to source
Leistiko ve ark. 2024 · Experiment · 58 participants
In 58 healthy adults, 40 Hz (gamma) binaural beats did not change attention-test performance (reaction time, errors, attention networks) compared with a control tone, and had no effect on a single-item self-rating of anxiety.
No significant difference from a control tone in attention measures or self-rated anxiety
First published online in 2023. Within-subject crossover with randomized order.
Leistiko NM, Madanat L, Yeung WKA, Stone JM. Effects of gamma frequency binaural beats on attention and anxiety. Curr Psychol. 2024;43(6):5032-5039. doi:10.1007/s12144-023-04681-3 PMID 37359672 Go to source
Melnichuk ve ark. 2025 · Experiment · 80 participants
Sixteen parameter conditions were tested; 80 undergraduates were randomized and 64 analysed. 40 Hz binaural beats with a low (340 Hz) carrier improved general attention performance but did not prevent the decline of attention over time. EEG showed a response at the beat frequency that varied with parameters and weakened under white-noise masking. The authors say the finding needs replication.
Higher hit rate than a pure tone for 40 Hz beats with a 340 Hz carrier (p = 0.002); no effect on the vigilance decrement
Melnichuk A, Cooper RK, Hawk LW. A parametric investigation of binaural beats for brain entrainment and enhancing sustained attention. Sci Rep. 2025;15(1):4308. doi:10.1038/s41598-025-88517-z PMID 39910150 Go to source
Hajós ve ark. 2024 · Randomised controlled trial · 76 participants
OVERTURE: a 6-month randomised, double-blind, sham-controlled trial in 76 people with mild to moderate Alzheimer's disease using a device that delivers light and sound together for 1 hour a day. It was safe and well tolerated. There was no statistical separation between active and sham groups on the primary clinical measure or two secondary cognitive measures; some secondary measures reached nominal significance.
Most authors are employees of, and hold stock options in, the company that makes the device. The trial was not powered to assess efficacy.
Hajós M, Boasso A, Hempel E, Shpokayte M, Konisky A, Seshagiri CV, Fomenko V, Kwan K, Nicodemus-Johnson J, Hendrix S, Vaughan B, Kern R, Megerian JT, Malchano Z. Safety, tolerability, and efficacy estimate of evoked gamma oscillation in mild to moderate Alzheimer's disease. Front Neurol. 2024;15:1343588. doi:10.3389/fneur.2024.1343588 PMID 38515445 Go to source
Last reviewed: 3 October 2026 · Next review: 3 April 2027