This study looks at neurodegeneration and dementia in people aged 50 to 90. Neurodegeneration means the brain is slowly getting worse, and dementia is when this affects things like memory and thinking. The study compares people with dementia and those without memory problems. Participants will visit one of 30 centers across Canada to provide samples like blood and saliva, and have tests such as brain scans. These tests help doctors see how the brain changes over time. They also check if there are any changes in memory or thinking each year.

To join, you should have some memory issues and be able to speak English or French. You also need a friend or family member to help you with the study. If you have Parkinson's Disease, you can still join. But if you have other serious brain issues or can’t have a brain scan, you should not participate.

• Study spans several years with annual follow-ups.
• Participants must visit a center for tests and sample collection.
• It's important you have a friend or family member to help during the study.