Inclusion Criteria:

1. Permanent residents of Harbin or Hainan who will continue to reside in Harbin or Hainan for the next 5 years.
2. Baseline age ≥60 years, with basic communication and comprehension abilities.
3. No confirmed diagnosis of end-stage major organic diseases (e.g., advanced heart failure, advanced liver failure, advanced kidney failure, malignant tumors).
4. Able to perform activities of daily living independently and capable of completing questionnaires and physical examinations.
5. Willing to participate in the study, provide written informed consent, accept long-term follow-up, and provide biological specimens.

Exclusion Criteria:

1. Occurrence of life-threatening acute events (e.g., myocardial infarction, acute heart failure, stroke) within the past 30 days.
2. Currently receiving chronic treatment with antiviral drugs (e.g., for HIV) or antipsychotic medications.
3. Presence of moderate to severe cognitive impairment preventing survey completion or follow-up cooperation.
4. Current acute infectious diseases such as influenza or fever.
5. Simultaneous participation in other interventional clinical studies.
6. Refusal to sign informed consent or unwillingness to provide biological specimens.
7. Any other condition deemed unsuitable for study participation by the investigators based on overall assessment.