Alzheimer’s and Parkinson’s are both diseases affecting the central nervous system 
 and they share some similar characteristics. Which of the following is only true for 
 Alzheimer’s disease?
 (a) Patients suffer from the degeneration of nerve cells in the brain.
 (b) Symptoms can be treated with medications that increase acetylcholine in the 
 brain.
 (c) It mostly affects people over the age of 55 and presently has no cure. 
 (d) Patients lack a neurotransmitter essential for normal brain functioning