This study looks at diseases that harm the brain and nerves, like *Amyotrophic Lateral Sclerosis (ALS)* and *Frontotemporal Dementia (FTD)*. These diseases sometimes make strange proteins build up in brain cells, causing problems with movement or thinking. The study aims to find out if these diseases have common causes or risks. People aged 18 and older with these disorders can join. The study involves a screening visit that may last 2-3 days, including tests like: - **Medical history and physical exams**: Doctors will ask about your health and check your body. - **Memory and movement tests**: You’ll do tasks like standing up quickly or walking to see how your body and brain work. - **Blood and lung tests**: These help doctors understand more about your health. You might also have an *MRI*, a special picture taken inside your body using a machine, and other optional tests. If you join, you might help researchers learn about these disorders. Participants might be contacted for future studies if they're not eligible now. **Key Points**: - Screening visit can last 2-3 days. - Tests include memory, movement, and medical checks. - Optional advanced tests like MRI and blood samples. **Note**: Participation is voluntary, and some tests are optional.