A prospective randomized controlled trial aimed at assessing if electroacupuncture (EA) combined with donepezil is more effective than donepezil for improving the cognitive function of AD patients. The hypothesis of this study is as follow:

• Is the short-term effect of EA combined with donepezil better than donepezil on improving cognitive function of patients with Alzheimer's disease after 12 weeks' treatment?
• Whether the effect of EA combined with donepezil on improving cognitive function can last until the end of 6 months' follow-up?

• Patient registry: Participants experiencing cognitive impairment will be recruited will be recruited at Guang'anmen Hospital, Beijing, China, via web or posters. A neurologist will make the diagnosis. Randomization will be performed by the pharmacological assessment center at Guang'anmen Hospital.

• Sample size: The calculation of sample size is based on the primary outcome that the change from baseline in ADAS-cog. According to previous studies [26], 39% of patients showed an improvement of at least 4 points on the ADAS-cog after treating by donepezil. We estimated the rate 39% in the donepezil group and 55% in the EA combined with donepezil group. 304 participants were needed to provide 80% power at a significant level of 5% using analysis of variance. The total sample size required for the study is 334 (167 each group) assuming a 10% loss to follow-up.

• Quality control

  1. Investigators participating in this trial will take a strict course about the process of randomization, manipulation of electroacupuncture, selection of patients, the whole process of this trial and request for filling out case report form in order to improve the internal consistency of observation between different researchers.
  2. The process of randomization will be under a rigorous control.
  3. This trial has a specific inclusion and exclusion criteria.
  4. Both outcome assessors and statisticians will be blinding.
  5. Patients will sign the informed consent voluntarily and a good relationship between researchers and patients will be established in order to improve patients' compliance. Participants will have a detailed record of the contact information easy for follow-up.
  6. The standard of the drugs, acupuncture apparatus, inspection equipment are consistent for the patients in the two groups.

• Outcome assessment, completion of case report forms and data management will be under a rigorous supervision.

Inclusion Criteria:

Participants meeting all of the following criteria will be included in this trial: 1) the diagnostic criteria of Neurological Communicative Disorders and Stroke and the Alzheimer Disease and Related Disorders Association (NINCDS-ADRDA) or the Operational Criteria for the Diagnosis of Alzheimer's disease (OCDAD), 2) aged between 60-85 years, 3) cognitive impairment based on the scores of the Chinese version of the Mini Mental State Examination (MMSE) (illiteracy group ≤19, primary school group ≤22, junior high school and high school group ≤23, and well-educated group ≤26), 4) absence of depression (via an emotional assessment), 5) Magnetic Resonance Imaging (MRI) confirmation of atrophy of the hippocampus or the medial temporal lobe volume, 6) the Medial Temporal Lobe Atrophy Rating Scale (MTA-scale) score (≥ 2 for those under 75 years, and ≥ 3 for those over 75 years).

Exclusion criteria:

Participants meeting any one of the following criteria will be excluded from this trial: 1) Cognitive impairment caused by other factors (e.g. vascular dementia, dementia with Lewy's bodies, frontotemporal dementia, hormone or metabolic abnormalities, hypothyroidism, folic acid or vitamin B12 deficiency, delirium or other mental and emotional disorders [such as schizophrenia and depression]), 2) a serious heart condition, hepatic disease, renal system disease, hematopoietic system disease, or malnutrition of the whole body, 3) aphasia or decreased vision that is severe, blindness, disturbance of consciousness, or participants who cannot cooperate with the related examinations due to physical disability, 4) anticoagulant treatments such as warfarin or heparin, 5) use of pacemakers or participants too afraid of acupuncture, or 6) acupuncture or donepezil treatment in the past 30 days.