Last updated: August 2026
This page promises nothing. It summarises what has been studied about 40-hertz stimulation — including the findings that argue against it. ThinkSync is a game, not a medical device, and treats nothing.
Rhythmic light and sound at 40 hertz produce a response at the same frequency in the brain. In Cognito Therapeutics’ clinical work this 40 Hz steady-state oscillation was reliably evoked in participants. This is the best-supported part: that the rhythm arrives in the brain. What follows from it is the open question.
The starting point is work from Li-Huei Tsai’s lab at MIT: Iaccarino et al., “Gamma frequency entrainment attenuates amyloid load and modifies microglia”, published in Nature in December 2016. In mice modelling Alzheimer’s disease, 40 Hz flickering light reduced amyloid load in the visual cortex, and microglia — the brain’s immune cells — clustered around the plaques.
Cognito Therapeutics, founded by Tsai and Ed Boyden, grew out of that work to test the approach in humans.
In the OVERTURE study, around 60 people with Alzheimer’s disease or mild cognitive impairment received one hour of combined 40 Hz light and sound stimulation daily for six months, against a sham treatment. The company reports slower decline in cognition and daily function, and preserved brain structure.
The context that belongs with it: this was an early study with a small number of participants, and the figures come from the manufacturer. A larger trial with 670 participants — the HOPE study — is under way. Its result is pending.
The findings are not undisputed. In 2023 several groups published work that could not confirm the animal experiment: a study in Nature Neuroscience found that 40 Hz light does not entrain native gamma oscillations in Alzheimer’s model mice; work in eNeuro found no reduction in amyloid load. Tsai’s group has raised methodological objections to those papers.
Anyone forming a view should know both sides. That is why they are both here.
The research concerns Alzheimer’s disease, largely in animal models and early clinical studies. There is no solid evidence for lasting improvement of concentration in healthy people. Nobody using ThinkSync should expect it.
A Sudoku in which light and sound pulse at 16 or 40 hertz — switchable off, individually, at any time. It is not a medical device, makes no diagnosis and treats nothing. If you are prone to seizures or sensitive to light, leave the light stimulation switched off.