There is no single test that can determine if a person has Alzheimer's disease. The diagnosis is made through a series of tests that help eliminate other possible causes. Until there is a conclusive test, doctors may continue to use the words "probable Alzheimer's disease." However, you should be aware that doctors making this diagnosis are accurate 80 to 90 per cent of the time.

Making the diagnosis can take time. If scans and other investigations are required, it could be 4-12 weeks, depending on waiting lists. If the person is in the early stages of dementia, a 6-12 month period of monitoring may be required before a diagnosis can be made.