Alzheimer’s disease is a chronic neurodegenerative disease that destroys brain cells, causing thinking ability and memory to deteriorate over time. Alzheimer’s disease is not a normal part of aging and is irreversible. While it’s difficult to predict symptoms, the order in which they will appear or the speed of their progression, there are some warning signs you can look out for. Sudden changes to your loved one’s personality are often another sign that something is not right. These changes can include anxiety, paranoia, depression, and socially inappropriate behaviors, as well as sudden mood swings and physical aggression.