1. Current research has found that tDCS has a positive effect on improving the negative attention bias of AD patients, and this study uses HD-tDCS intervention to improve the cognitive function and neural mechanisms of AD patients in the OFC to provide a theoretical basis for AD neural mechanism research. Verify Hypothesis 1: HD-tDCS cathodal stimulation of the left OFC reduces the excitability of this region, modulates its connectivity with the attentional function network, and thus changes the emotional experience of social threat.
2. Currently, there is no consensus on the stimulation parameters for tDCS in the treatment of AD, and more evidence is needed to prove and explore. It is hoped that the HD-tDCS intervention protocol will become an effective treatment method for improving cognitive function and clinical symptoms in AD patients. Hypothesis 2: The HD-tDCS with intensified stimulation parameters (2mA, twice a day, with a 20-minute interval, for 5 consecutive days) has an impact on the main and secondary clinical variables of AD patients.

Inclusion Criteria:

1. Meet the DSM-5 AD diagnostic criteria;
2. The Chinese version of the Brief International Neuropsychiatric Interview (MINI) screening meets the diagnosis;
3. Age: 18-55 years old;
4. The patient participated voluntarily, obtained the consent of the family members, and signed the informed consent form;
5. Scale score criteria: 14 points on the Hamilton Anxiety Scale (HAMA) and 17 points on the Hamilton Depression Scale (HAMD).

Exclusion Criteria:

1. Neurological diseases or other psychiatric disorders;
2. severe somatic diseases;
3. received medical treatment including medication, psychotherapy, electroconvulsive therapy, and physical therapy within the first half months of enrollment;
4. tDCS examination contraindications, such as intracranial metal or electronic implants, skull plate, or other skull implants.
5. Pregnancy and lactation.