Clinical Research Directory

Inclusion Criteria: China HEAD Community Cohort: 1. Resident in a Chinese community. 2. Aged 50-79 years. 3. Have adequate vision and hearing (with glasses or hearing aids if necessary), and be able to walk, communicate, and complete study-related assessments (including questionnaires, physical examinations, neuropsychological assessments, and biospecimen collection) independently or with assistance. 4. Willing to provide written informed consent for baseline assessments, follow-up, biospecimen donation, and data collection. China HEAD Familial Sub-cohort: 1. Resident in a Chinese community. 2. Aged 18 years or older. 3. Have a family history of Alzheimer's disease (AD) involving at least two first-degree relatives across at least two consecutive generations, with AD diagnoses previously established at tertiary hospitals and verified through medical history. 4. Meet the 2011 National Institute on Aging-Alzheimer's Association (NIA-AA) diagnostic criteria for AD. 5. Have adequate vision and hearing (with glasses or hearing aids if necessary), and be able to walk, communicate, and complete study-related assessments (including questionnaires, physical examinations, neuropsychological assessments, and biospecimen collection) independently or with assistance. 6. Willing to provide written informed consent for baseline assessments, follow-up, biospecimen donation, and data collection. Exclusion Criteria: The following exclusion criteria apply to participants in the HEAD study: 1. Refusal to provide written informed consent. 2. Refusal to participate in questionnaires or other data collection procedures. 3. Refusal to provide blood or other biological samples. 4. Self-reported stroke events (e.g., cerebral hemorrhage or cerebral infarction) within the past six months. 5. Self-reported diseases potentially impairing cognition, including congenital intellectual disability, intracranial tumors, epilepsy, Parkinson's disease, or severe psychiatric disorders such as schizophrenia requiring medication. 6. Self-reported major organ failure (e.g., liver or kidney failure), malignancy, or other conditions associated with a shortened life expectancy that prevent completion of follow-up assessments. Additional exclusion criteria for participants undergoing magnetic resonance imaging (MRI): 1\. Inability to tolerate MRI examinations or contraindications to MRI, including claustrophobia; MRI-incompatible implanted pacemakers, aneurysm clips, artificial heart valves, cochlear implants, or other metallic implants; or other clinical conditions or examination findings that investigators consider potentially harmful during MRI.