I want to understand how cognitive problems are evaluated
There isn't one single “dementia test.” A cognitive evaluation usually involves several pieces — a careful history, cognitive assessment, and medical evaluation — and not everyone needs every test.
There isn't one dementia test.
Clinicians build a picture from multiple pieces. No single test tells the whole story. The evaluation is a process that combines information from several sources to understand what's happening and why.
The story
What changed, when it began, how it has progressed, medical history, medications, family observations, and the impact on everyday function. This is the most important part of the evaluation — it guides everything that follows.
Cognitive assessment
Brief cognitive tests (such as the MoCA or MMSE) evaluate memory, language, attention, and other thinking skills. They are screening tools — not diagnostic tests. They help identify whether a problem exists and where it might be, but they don't identify the cause. When more detailed information is needed, neuropsychological testing can provide a deeper picture across multiple cognitive domains.
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Medical evaluation
A neurologic and physical examination looks for signs that may point to specific conditions. This includes assessing movement, reflexes, sensation, and other neurologic functions, as well as screening for medical conditions that can affect cognition.
Laboratory testing
Labs look for medical conditions that can cause or worsen cognitive symptoms — such as thyroid disorders, vitamin deficiencies, metabolic abnormalities, or infection. There is no single universal lab panel; tests are selected based on the clinical picture and what the evaluation has revealed so far.
Brain imaging
Structural imaging — MRI or CT — looks at the physical structure of the brain: atrophy, strokes, tumors, fluid, or bleeding. PET imaging answers different questions. Amyloid PET detects amyloid plaques. Tau PET detects tau tangles. FDG PET shows brain metabolism. Each type of imaging provides a different piece of information.
Biomarkers
Amyloid and tau biomarkers can be measured in blood, cerebrospinal fluid (CSF), and PET imaging. These tests can indicate whether Alzheimer's pathology is present. Their appropriate use depends on the clinical situation — not everyone needs biomarker testing, and a result is only meaningful when interpreted alongside the clinical picture.
Putting the pieces together
Results need to be interpreted together rather than individually. A single abnormal result doesn't make a diagnosis. The clinical picture — symptoms, function, history, exam, and test results — guides interpretation. This is why the evaluation is a process, not a single test.
Prepare for your appointment
The Diagnostic Checklist helps you organize what you've noticed, what to bring, and what questions to ask. It's designed to make the most of your time with your clinician.