Which of the following statements correctly contrasts Alzheimer's and Parkinson's Disease?

Alzheimer's is a neurological disorder while Parkinson's is a physical one.
Alzheimer's affects only individuals over 70 while Parkinson's can strike at any age.
Parkinson's affects primarily the systems in the brain that affect movement while Alzheimer's affects other systems first.
Parkinson's causes tangles of damaged neurons while Alzheimer's causes overall atrophy of the brain.