Effect and Safety of Non-invasive Electrical Stimulation in Alzheimer's Disease

Effect and Safety of Non-invasive Electrical Stimulation in Improving Cognitive and Depressive Symptoms in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder, characterized primarily by cognitive impairment as its main clinical symptom, often accompanied by emotional disturbances such as depression and anxiety, imposing a significant disease burden. Temporal Interference Stimulation (TIS) is an emerging non-invasive electrical stimulation technique that precisely targets deep structures within the hippocampus through interference of multiple electric fields. This study will administer a two-week TIS treatment to patients with AD co-occurring depression, targeting the hippocampus, and compare changes in patients' cognitive function, scores on depression and anxiety scales, and functional magnetic resonance imaging (fMRI) data before and after treatment. An emotional word recall task will be administered during fMRI scans. The aim of this study is to investigate the efficacy, safety, and neural mechanisms of TIS-mediated modulation of hippocampal circuits in improving cognitive and emotional functioning in patients with AD and comorbid depression.

Inclusion Criteria:

• (1) Right-handed, Han ethnicity; (2) Meet the clinical diagnostic criteria for Alzheimer's disease as defined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5); (3) Age ≥60 years, with at least primary school education, and capable of cooperating during testing; (4) Mini-Mental State Examination (MMSE) score <24; (5) Clinical Dementia Rating (CDR) score of 0.5 or 1; (6) The 24-item Hamilton Depression Scale (HAMD-24) score ≥20.

Exclusion Criteria:

• (1) Systemic diseases causing cognitive impairment, such as hypothyroidism, vitamin B12 or folic acid deficiency, and acquired immunodeficiency syndrome; (2) Comorbid neurological disorders including epilepsy, Parkinson's disease, normal-pressure hydrocephalus, and brain tumors; (3) Comorbid mental illnesses such as schizophrenia, bipolar disorder, or psychiatric disorders due to alcohol or drug abuse; (4) History of post-traumatic loss of consciousness, intracranial infection, or cerebrovascular disease; (5) A Hachinski Ischemic Scale (HIS) score ≥4; (6) Cranial MRI revealing ischemic lesions involving critical brain regions like the hippocampus, thalamus, basal ganglia, or angular gyrus, or multiple ischemic lesions in deep gray matter of the cerebral hemispheres; (7) Inability to undergo MRI due to special conditions such as internal metal implants or pacemakers.