The National Institute on Aging and the Alzheimer's Association are suggesting changes to the research definition of Alzheimer's disease. There are new criteria to define what Alzheimer's disease is and who has it — but only as it relates to clinical trials and research, and not the diagnosis in your doctor's office.

Previously, Alzheimer's disease dementia was characterized by symptoms such as memory loss and changes in thinking and cognition. And that's still the case when your doctor diagnoses Alzheimer's disease dementia.

The proposed research definition of Alzheimer's is defined by the presence of biomarkers — a buildup of plaques and tangles in the brain — which are identified by imaging scans of the brain and samples of cerebrospinal fluid. This change allows researchers to better design clinical trials, include the right participants and learn more about the disease in its earlier stages.

Here's why it's important: The classic symptoms of Alzheimer's disease don't define or diagnose it. They're a complication of the changes in the brain that do define the disease — and these brain changes can occur long before the symptoms show up. This change in research may lead to earlier diagnosis of Alzheimer's disease, which will hopefully lead to delayed progression and better treatments.