Effect of Transcranial Alternating Current Stimulation(tACS) for Early Alzheimer's Disease

EEG recordings were obtained from each subject based on 64 electrode locations of the International 10-20 system (sampling frequency 1000Hz).The recorded EEG data were filtered with a second order band-pass Butterworth filter with cutoff frequencies of 0.5 and 60 Hz. For each testing condition, data with muscular, ocular and other types of artifacts were manually discarded and 60 seconds of stationary EEG signal were selected. Only these segments were accepted for further analysis.

The analysis in the frequency domain was performed using Welch's periodogram method. Recordings were segmented into tracts of 10 seconds each, windowed with a Hanning window, with 50% overlap. The relative powers of the spectral components in the typical spectral bands delta (δ: 0.5-4 Hz), theta (θ: 4-8 Hz), alpha1 (α1: 8-10.5 Hz), alpha2 (α2: 10.5-13 Hz), beta1 (β1: 13-20 Hz), beta2 (β2: 20-30 Hz) and gamma (γ: 30-60 Hz) were computed by dividing the absolute power in each band by the total power.

The associative memory test uses facial cue word recall. The subjects memorized 20 photos of faces displayed on a screen in gray scale for 4 seconds each. When each card was presented, a common word appeared alongside the face. The subjects had to remember associations between faces and words by association. After a delay of about a minute after the study ended, the subjects were shown 12 of the same faces in different random orders, instructing them to recall the words that appeared with each face during the study. Recorded the correct number of words each face recalled. The faces were taken from a database of 24 amateur models. Each test format included only male or female faces.

The full name of MMSE is mini-mental state examination, and the scale consists of 30 subject, include the following seven aspects: time orientation, place orientation,immediate memory,attention and calculation,delay memory,language, visual space.One point is awarded for each question correctly answered during MMSE evaluation. If subject give the wrong answer or don't know answe he/she awarded 0 score, scope of scale score of 0 to 30 points. The higher the score, the better.

The changes in LMT will constitute the secondary research outcome

The changes in DST will constitute the other research outcome.

The Trail Making Test (TMT) is divided into two parts, part A and part B. Part A requires the subject to connect 25 Numbers on the paper in sequence, and part B requires the subject to connect 25 Numbers of different colors alternately in sequence. The time it takes for the subject to complete all the Numbers is the subject's final score.

The changes in HAMD will constitute the other research outcome. The examination content consists of 17 questions (about 10 minutes), with a full score of 52. The higher the score, the more severe the depressive symptoms are.

The changes in HAMD will constitute the other research outcome. The examination content consists of 14 questions (about 10 minutes), with a full score of 56. The higher the score, the more severe the anxiety symptoms are.

The changes in HAMD will constitute the other research outcome.

MoCA was developed by Nasreddine et al. based on clinical experience and reference to the MMSE cognitive items and scores, and the final version was finalized in November 2004. We adopted a localized version (Mandarin version，includes 2 alternative versions) in line with the Chinese cultural background.It includes 11 inspection items in 8 cognitive fields, including visual structure skills, executive function, naming, attention and calculation, language, abstract thinking, memory, and orientation. With a total score of 30 or more than 26, it is normal. Anyone who has been education for less than 12 years will need to add one point to his final score.

The Geriatric Depression Scale (GDS) was created in 1982 by Brank et al. and is dedicated to screening for depression in the elderly. The most suitable feelings for the elderly in the past week were evaluated.There are 30 items in the scale, the total score is 30 points. The higher the score, the more obvious the depressive symptoms. It is generally considered that less than 10 points is normal.

The JLOT test was determined by Benton et al. in 1994. There are two versions of H and V. The difference is that the order in which the pictures are presented is different. Each version contains 35 images, of which the official test consists of 30 images, and the other 5 images are for the participants to learn. The final score is the correct number of subjects to answer, the full score is 30 points, the higher the score, the better the space perception ability of the subject.

The changes in HVOT(Hooper visual organization test Hooper visual organization test) will constitute assess response to rTMS the secondary research outcome measure.HVOT is a cognitive test used to evaluate the perceived structure of the subject. It consists of 30 items，and each question is 1 point and the total score is 30 points. The final score is the correct number of subjects to answer, the full score is 30 points, the higher the score, the better the space perception ability of the subject.

The Stroop color word test was developed by Stroop in 1935 and is used to evaluate the attention function of the subject. The subject is required to correctly read the target color on the stimulus card and record the completion time. The final completion time is the score of the participant. The shorter the time used, the better the performance of the subjects.