Establishment of the Chinese Preclinical Alzheimer's Disease Study With Multiple Neuroimaging

This study is building a Chinese research database of people who are cognitively normal but may be at risk for Alzheimer's disease, using advanced brain scans and other tests. The goal is to better understand how Alzheimer's develops before symptoms appear. **You may be eligible if...** - You are between 45 and 90 years old - You are cognitively normal (no memory or thinking problems), scored as normal by a clinician - OR you have been diagnosed with mild cognitive impairment or early Alzheimer's disease - You have no other significant neurological conditions, major chronic illnesses, or cancer - You are able to give written informed consent **You may NOT be eligible if...** - You have another neurological disease affecting cognition or movement - You have a family history of Alzheimer's or related neurological conditions (for the healthy control group) - You are unable to undergo the required brain imaging scans - You have a serious medical condition that would interfere with participation Talk to your doctor to see if this trial is right for you.