Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive dysfunction and behavioral impairment. It is currently the most common type of dementia in the old age. At present, the clinical treatment of Alzheimer's disease is expensive and has side effects, so it is very important to explore new methods of treatment for AD. Investigators designed a prospective, randomized, double-blinded and placebo-controlled trial to investigate the effect of transcranial alternating current stimulation (tACS) on cognitive function in AD patients and to assess the biological effectiveness of the treatment.

As the population is aging, there is an urgent need to develop new methods of treatment for AD. Noninvasive neuro-regulation is a new technique in treating neuropsychiatric diseases. It include transcranial magnetic stimulation, traditional transcranial direct current stimulation, traditional transcranial alternating current stimulation and etc. Previously, conventional transcranial direct current stimulation had shown inconsistent results in the treatment for AD. This may be related to the low current density of traditional electrical stimulation in deep brain areas, such as hippocampus and amygdala, and leading to poor stimulation effect. Compared with the traditional transcranial electrical stimulation technology, the high intensity tACS greatly improves the current intensity, so that the electric field intensity to the deep brain nucleus during stimulation is greatly increased, and it avoids side effects such as burning sensation. Therefore, it could be used for AD patients. However, there are few clinical studies on high intensity tACS on AD, so investigators designed a randomized double-blinded placebo-controlled trial to explore the effect of high-current tACS on AD. At the same time, multimodal functional brain imaging before and after treatment will be used to compare the changes of brain function activation and cerebral hemodynamics in AD.

Inclusion Criteria:

1. Meet the diagnostic criteria of National Institute on Aging and Alzheimer's Association (NIA-AA) 2011 for Alzheimer's disease, Clinical Dementia Rating (CDR) score is greater than or equal to 0.5 and less than or equal to 1, and amyloid PET imaging is positive.
2. Have the ability to cooperate with neuropsychological testing, EEG measurement, and MRI examination;
3. Have willingness to undergo cognitive psychological evaluation;
4. Do not have cognitive impairment due to other degenerative diseases or viral and immune encephalitis;
5. The length of schooling is at least 3 years.

Exclusion Criteria:

1. Do not suffer from severe depression, anxiety and other mental illness;
2. Do not suffer from major diseases such as tumors, heart and lung diseases, nervous system diseases, etc.
3. Do not have been diagnosed with other dementia such as Parkinson's disease dementia (PDD), frontotemporal dementia (FTD), lewy body dementia (DLB), and normal cranial pressure hydrocephalus (NPH).

After the research is published in an academic journal, a link to the laboratory website will be provided in the article so that others can view supplementary materials, etc. Access to the data requires the consent of the principal investigator and the ethics committee.

After the research is published in an academic journal, a link to the laboratory website will be provided in the article.

Access to the data requires the consent of the principal investigator and the ethics committee.

Investigators designed a double-blinded trial in which neither the investigator nor the subjects know whether they will be received the treatment or a placebo.