Central Nervous System
- the complex of nerve tissues that controls the activities of the body. In vertebrates it comprises the brain and spinal cord.
Peripheral Nervous System
- the nervous system outside the brain and spinal cord.
It is a chronic neurodegenerative disease that usually starts slowly and gets worse over time. The most common early symptom is difficulty in remembering recent events (short term memory loss). As the disease advances, symptoms can include: problems with language, disorientation (including easily getting lost), mood swings, loss of motivation, not managing self care, and behavioural issues. As a person's condition declines, she or he often withdraws from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the average life expectancy following diagnosis is three to nine years