A Prospective Cohort Study of Multimodal Biomarkers and Progression From Mild Cognitive Impairment to Dementia

Inclusion Criteria: General criteria: 1. Age 50 years or older. 2. Male or female. 3. Able and willing to comply with the study assessments and follow-up procedures. 4. Able to provide written informed consent, or written informed consent is provided by a legally authorized representative when applicable. Dementia cohort: 1. Diagnosis of dementia established by consensus among three senior neurologists with experience in cognitive disorders. 2. Clinical Dementia Rating score of 1 or higher. 3. Availability of a Chinese-speaking caregiver who can provide information about the participant's clinical condition and who lives with or has contact with the participant for at least 4 days per week. Mild cognitive impairment cohort: 1. Diagnosis of mild cognitive impairment established by consensus among three senior neurologists with experience in cognitive disorders. 2. Clinical Dementia Rating score of 0.5. 3. Availability of a Chinese-speaking caregiver who can provide information about the participant's clinical condition and who lives with or has contact with the participant for at least 4 days per week. Cognitively unimpaired cohort: 1. No history of a major neurological or psychiatric disorder. 2. Clinical Dementia Rating score of 0. Exclusion Criteria: 1. An acute neurological disorder, including acute stroke, or another medical or neurological condition that would prevent valid assessment of cognitive status. 2. A severe psychiatric disorder that would interfere with cognitive assessment or study participation. 3. Terminal malignant disease or another severe medical condition that would prevent completion of the study procedures. 4. Severe visual or hearing impairment that would interfere with neuropsychological assessment. 5. Inability or unwillingness to complete the planned 12-month follow-up.