A loss of ability to store and retrieve memories. Everyone forgets things from time to time; this is normal. Memory impairment occurs when there is damage to the physical processes of memory storage and retrieval that take place in the brain. Such damage can occur through trauma (head injury), stroke, or neu-rodEgEnErativE diseases (Alzheimer’s, Parkinson’s, Huntington’s) and as a consequence of changes that take place in the brain through normal aging (apoptosis, diminished blood supply due to atherosclerosis or arteriosclerosis). Memory impairment significantly affects cognitive Function. Some degree of memory impairment is common in the later stages of Parkinson’s disease, particularly in older people.