Temporal 40 Hz lowered memory-test errors versus sham by week 16
Q: Did temporal 40 Hz stimulation change memory scores?
A: In a 2026 randomized double-blind trial, people with Alzheimer's who received 40 Hz current over both temples had lower error scores on a memory test after 4 weeks, and the lower score was still there at week 16. The sham group did not show that change.
Who sat for the sessions
The visits were at Ningbo Kangning Hospital in China, from September 2023 to December 2024. The people were adults aged 55 and older with Alzheimer's disease. They were right-handed, and they stayed on the same dose of donepezil. One hundred people were assigned by chance, 50 to each group. The mean age was about 73 in both groups, and about 6 in 10 were women. Forty-five people in each group finished the 4-week course. The comparison that carried through to week 16 used 42 people in the active group and 43 in the sham group.
What the two groups received
Both groups came to the hospital twice a day, five days a week, for four weeks. Each visit lasted 20 minutes, with at least four hours between the two visits that day. That was 40 visits in all. Pads about 4 centimeters square sat over both temples. The hospital used a stimulator from Kerfun Medical, set to 40 Hz.
The active group received 40 Hz at 2 milliamps for the full 20 minutes. The sham group felt the current rise to 2 milliamps for about 30 seconds, then it stopped. People did not know which group they were in. The staff who scored the tests did not know either.
If you want to sit with that same number, open 40 Hz Gamma - Memory Enhancement. A library session is a tone you can hear. It is not the hospital current, and the current strength is not in the tone.
What changed on the memory test
The main test was the Alzheimer's Disease Assessment Scale, cognitive subscale. A lower score means fewer errors. In the active group the total score moved from 23.89 at the start to 18.83 at week 4, then 19.38 at week 16. That was a mean drop of 5.057 points by week 4, and 4.507 points by week 16. The sham scores were 24.13, then 22.74, then 25.19. The sham change over time was not a clear result. The difference in how the two groups changed over time was clear (p=0.010). At week 16 the active group's total score was still lower than the sham group's (p=0.040 after correction).
The memory part of the same test showed the same pattern (p=0.007 for the change over time). Active memory scores moved from 16.173 to 13.164 at week 4 and 13.071 at week 16. Sham memory scores stayed near where they started. The praxis part also differed (p=0.002). By week 16 the sham group's praxis score had worsened, from 2.047 to 3.116, while the active group stayed near its starting score.
A scalp imaging measure found stronger links among 18 frontal and parietal regions in the active group (p=0.010 after correction). That is a lab finding from the same visits, not a score a family would read at the kitchen table.
What stayed the same
The Mini-Mental State Examination did not show a clear difference between the groups over time (p=0.075). Attention and language on the longer test also stayed without a clear group difference. The benefit that held was the drop in error scores, especially memory and praxis, not every test in the visit.
No serious adverse events were reported across the 4-week course and the follow-up. In the active group, 2 people had a mild headache and 5 had dizziness. In the sham group, 3 people had a mild headache and 3 had dizziness. Those events settled within an hour.
This was one hospital, and the final comparison was 85 people. The diagnosis was made in clinic, without a required brain scan. The sessions lasted 4 weeks, and the last score was at week 16. A larger set of hospitals would be the next test of the same setting.
Where to read the paper
The paper is by Rong Guo, Xingxing Li, Chenjun Zou, Chao Zheng, Xiaohong Wu, Xuechao Lu, Jiaying Yan, Junfang Zhang, Xiaoyan Luo, Shiwei Ye, and Dongsheng Zhou. It was published in Advanced Science in 2026. The title on the journal page is Temporal-Targeted Accelerated 40 Hz tACS Enhances Cognitive Function and Network Integration in Alzheimer's Disease: A Randomized Clinical Trial.
Read the full text at PMC13616376, or the PubMed record at PubMed 42801558.
KYMA is working to establish a science-based podcast, because reliable information about this topic is almost impossible to find on ordinary social media.
| Result | What the paper reported |
|---|---|
| Memory errors by week 4 | The active group dropped 5.057 points on the ADAS-Cog total score. The sham change over time was not a clear result. |
| Still lower at week 16 | The active group's total score remained lower than the sham group's (p=0.040 after correction). The mean drop from the start was 4.507 points. |
| Memory subscale | The memory scores fell in the active group and stayed down through week 16. The difference in change over time was p=0.007. |
| Other tests | The Mini-Mental State Examination did not show a clear group difference over time (p=0.075). Attention and language also stayed without that change. |
Related tones in the KYMA library
Open 40 Hz Gamma - Memory Enhancement and 40 Hz Gamma - Brain Health if you want a stored program for memory and brain health. They already store 40 Hz, the same number the hospital set on the temporal current. The current strength is not in the tone.
Extended 40 Hz session for memory consolidation and cognitive enhancement based on MIT research. · 30 min
Primary gamma frequency researched by MIT for Alzheimer's and brain health (PMC6547462). Promotes neuroplasticity, memory consolidation, and immune response in the brain. · 20 min
40 Hz frequency promotes cognitive function, enhances neural connectivity, and supports mental clarity and focus for overall brain health. · 5 minutes
Frequently asked questions
Why is 40 Hz Gamma - Memory Enhancement the row for this topic?
Open 40 Hz Gamma - Memory Enhancement because that row already stores 40 Hz, the same number the hospital set over both temples, and the measured change was on a memory test. 40 Hz Gamma - Brain Health also stores 40 Hz for this topic. The 40 Hz row stores the same number. The current strength is not in the tone. This study did not test these library rows.
What did the two groups receive over 16 weeks?
Both groups came in twice a day for 4 weeks, 20 minutes a visit, with pads at both temples. The active group received 40 Hz at 2 milliamps for the full 20 minutes. The sham group felt a short rise to 2 milliamps, then the current stopped. Scores were read again at week 16.
What stayed the same on the other tests?
The Mini-Mental State Examination did not show a clear difference between the groups over time. Attention and language on the longer test also stayed without that change. The benefit that held was the drop in ADAS-Cog error scores, especially memory and praxis.