Setting aside the notion of determining the number of individual animals on the planet for a moment, merely determining the number of species on the Earth is challenging. Science has only been able to offer estimates thus far, and totals vary greatly.
People who have early onset Alzheimer's may be in any stage of dementia â early stage, middle stage or late stage. The disease affects each person differently and symptoms will vary. If you are experiencing memory problems: 1  Have a comprehensive medical evaluation with a doctor who specializes in Alzheimer's disease.
Corticobasal Degeneration. Corticobasal degeneration (CBD) is a rare neurological disease associated with progressive brain degeneration. The disease, also known as corticobasal ganglionic degeneration, leads to the loss of brain tissue in the cortex, or outer layer of the brain, especially the area in the upper, front section of the brain.