What parts the of the nervous system that are affected by down syndrome?

Down's Syndrome. This syndrome has multiple physical effects, but the primary part of the nervous system affected is the brain. Intellectual development will be limited, and so will judgment, attention span, etc. Learning will be slow. For more information: http://tinyurl.Com/3c4rwpl.
Down syndrome. Mean total brain volume is reduced (microencephalopathy), and the cerebellum volume decreased.