Preclinical Alzheimer's disease

Alzheimer's disease begins long before symptoms are noticed. This stage is called preclinical Alzheimer's disease. It's usually identified only in research settings. You and those around you won't notice symptoms during this stage.

This stage of Alzheimer's can last for years, or even decades. Although you won't notice any changes, new brain-imaging technologies can identify amyloid plaques and neurofibrillary tangles. Tangles develop when proteins called tau change shape and organize into structures. These are common signs of Alzheimer's disease. These signs are called biomarkers. Biomarkers are substances or processes in the body that help your healthcare professional identify a health condition or what's happening in your body.

The ability to identify these early changes is especially important for clinical trials. Ongoing trials are looking at whether treating people with preclinical Alzheimer's may delay or slow the onset of symptoms. Imaging technologies also are important as new treatments are developed for Alzheimer's disease.

Additional biomarkers have been found in blood samples and may indicate an increased risk of Alzheimer's disease. These biomarkers can be used to support the diagnosis of Alzheimer's disease, typically after symptoms appear.

Genetic tests also can tell you if you have a higher risk of Alzheimer's disease, particularly early-onset Alzheimer's disease. These tests aren't recommended for everyone. You and your healthcare professional can discuss whether genetic testing might be helpful for you.

Newer imaging techniques, biomarkers and genetic tests will become more important as new treatments for Alzheimer's disease are developed.