Memory loss can be a symptom of brain malfunction. It is one of the most common reasons that people, particularly older people, visit a doctor. Sometimes family members notice and report the memory loss. The biggest concern for the person, family members, and doctors is usually whether the memory loss is the first sign of Alzheimer disease, a progressive and incurable form of dementia (a type of brain disorder). People with dementia have lost the ability to think clearly. Usually, if people are aware enough of their memory loss to be concerned about it, they do not have early dementia.