How is Alzheimer's Disease Diagnosed? - Genivity
Alzheimer’s disease is often a terrifying and debilitating diagnosis for both patients and their families. What can make this neurodegenerative disorder even more challenging is the fact that there is not yet a truly definitive way to diagnose the disease when a person is alive. Alzheimer’s disease is the most common form of dementia and, with a growing percentage of the US population advancing in age, researchers are working to discover newer and better ways to diagnose this condition. Here is an outline of the kinds of tests typically used to detect Alzheimer’s disease.

Clinical judgment

Clinical judgment is by far the most common way that people receive a diagnosis of Alzheimer’s disease. Memory impairment is the most common symptom of Alzheimer’s disease and it is also often the earliest symptom detected. Clinicians will have a heightened suspicion for the disease in patients older than age 65, unless there is a known history of early-onset Alzheimer’s disease in the family. A medical provider will look for clues like changes in language function, visuospatial skills and, later, changes in behavior. He or she may refer to the clinical criteria established by the National Institute on Aging and Alzheimer’s Association workgroups.

Neurocognitive evaluations

These are ways of evaluating specific types of memory, and other aspects of cognition, in the most objective fashion possible. To assess for Alzheimer’s, there are quick bedside tests, such as the Mini-Mental Status Exam (MMSE) and mini-cog, as well as formal neuropsychological evaluations.

Neuroimaging

An MRI of the brain can help tease out other possible causes of memory loss, including bleeding, tumors and problems with cerebrospinal fluid. Alzheimer’s disease cannot be definitively diagnosed from an MRI, however signs of the condition (such as brain atrophy and white matter lesions) can help point to the diagnosis. Scans that evaluate the brain’s function (as opposed to its anatomy), like PET scans, can also be used.

Biomarkers

Biomarkers are emerging as ways to detect Alzheimer’s disease but none are currently recommended for routine diagnostic purposes in primary care. A biomarker is a protein that is linked to Alzheimer’s disease that can be detected in the cerebrospinal fluid, serum (blood) or even saliva. Some specialists are already using biomarkers in practice to help them make Alzheimer’s diagnoses in patients with a complicated presentation.

Exclusion of other diagnoses

Clinicians should consider other types of dementia, like vascular, frontotemporal, Lewy body or Parkinson-related dementia, when considering a diagnosis of Alzheimer’s disease. Medication interactions, depression, hypothyroidism and Vitamin B12 deficiencies should also be explored.

Direct examination of brain tissue

The only definitive way to diagnose Alzheimer’s disease is to examine brain tissue under the microscope. Because this is very difficult to do in a living patient, conclusive Alzheimer’s diagnoses are typically made upon autopsy.