However, unlike normal aging Alzheimer's eventually escalates into frank confusion and profound memory loss. Beginning around age 30, there is a slow and steady decline in brain weight in normal brains, with age-related atrophy visible on CT images of the brain by the early 40's. Brain cell loss is not uniform, with the greatest loss in the hippocampal and frontal regions of the brain - those areas responsible for memory. With normal aging, the ability to create new memories is not usually impaired. Rather, it is the retrieval of memories that becomes troublesome.
Individuals are usually acutely aware of their lapses in memory.
In contrast to normal aging, Alzheimer's disease impairs the brain's ability to create new memories. No amount of reminders will help to retrieve information, because it was never encoded in the first place. Another unique signature of Alzheimer's is the unawareness of symptoms that patients express. Although clinicians once assumed this was a psychological denial, it turns out that unawareness is a neurological phenomenon. The frontal lobe function of self monitoring, and the ability to remember that one is forgetting, is compromised by the disease.