At some point, the damage occurring in the brain begins to show itself in very early clinical signs and symptoms. Much research is being done to identify these early changes, which may be useful in predicting dementia or Alzheimer's disease.
The course of Alzheimer's disease is not the same in every person, but symptoms seem to develop over the same general stages. In most people with Alzheimer's, symptoms first appear after age 60.
Memory problems are typically one of the first signs of Alzheimer's disease. Sometimes, other thinking problems, such as trouble finding the right words or poor judgment, are most prominent early on.
For more information, see About Alzheimer's Disease: Symptoms.