Multimodal Ophthalmic Imaging and Plasma Biomarkers for the Early Detection of Alzheimer's Disease

This study is investigating whether special eye scans and blood biomarkers can detect early signs of Alzheimer's disease before symptoms become severe. The retina (the back of the eye) may reflect changes happening in the brain, offering a non-invasive way to catch the disease earlier. **You may be eligible if...** - You are 50 or older (male or female) - You have been diagnosed with Alzheimer's disease, mild cognitive impairment, subjective cognitive decline, or are cognitively healthy and willing to participate as a comparison group - You are able to give informed consent **You may NOT be eligible if...** - You have another neurological condition (other than Alzheimer's) that could cause cognitive problems - You are unable to cooperate with cognitive testing - You refuse to have a blood sample taken Talk to your doctor to see if this trial is right for you.