Occasional forgetfulness, primarily of new information, such as names of people you recently met. Considered a normal response to aging.MILD COGNITIVE IMPAIRMENT
Severe or frequent memory lapses, such as repeatedly missing appointments, but no other mental impairment. About 40% of people diagnosed with MCI develop Alzheimer's within three years.DEMENTIA
Severe cognitive decline, marked by large memory deficits. Dementia is a not a disease but a symptom of a number of diseases, including stroke, substance abuse, head trauma, and Alzheimer's.ALZHEIMER'S
A progressive brain disease that initially causes mild memory loss and eventually destroys all cognitive functions, leading to death. Alzheimer's is responsible for about 50% of all dementia cases.