Alzheimer's disease is a disease of the central nervous system that causes "dementia." Dementia is a condition that is marked by the loss of the ability reason, plan, think, and remember. Dementia and Alzheimer's are not the same. Dementia is a name given to a set of symptoms and has many causes. Of the several diseases that cause dementia, Alzheimer's disease is the most common.
Alzheimer's disease is a chronic, degenerative disease that destroys brain cells. It causes a decline in mental function. The course of the disease is usually slow. As the disease attacks the brain, it robs the patient of the ability to control emotions, practice complex reasoning, recognize patterns, use judgment, speak, or remember. During the final stage of Alzheimer's, the patient loses all memory and mental functioning.
Often, it is not the patient that notices the first Alzheimer's disease symptom. Family members or a spouse will make note of forgetfulness or other memory impairment. Patients may mention an increased difficulty with learning new information, or handling tasks such as balancing the checkbook. Many will seek treatment after experiencing an Alzheimer's symptom that frightens them, such as losing their way home from the grocery store or forgetting the way to the bathroom. A few patients will experience falls, hallucinations, and changes in personality early in the course of the disease.