Checking for dementia involves several layers of testing, usually starting with brief cognitive screening in a doctor’s office and expanding to blood work, brain imaging, and sometimes specialized biomarker tests. The full process typically takes two to three visits and can span several weeks, depending on how quickly results come back and whether additional testing is needed.
Cognitive Screening Tests
The first step is almost always a short pen-and-paper test done in the office. Two screening tools dominate clinical practice: the Mini-Mental State Exam (MMSE) and the Montreal Cognitive Assessment (MoCA). Both are scored out of 30 and take roughly 10 to 15 minutes.
The MMSE tests six areas: orientation (knowing the date, where you are), registration, attention and calculation, recall, language, and visuospatial ability. A score of 24 or above is considered normal. The MoCA covers eight domains, adding abstract reasoning, executive function, and delayed recall to the mix. Its normal cutoff is slightly higher, at 26 out of 30, and it adds a point for people with fewer than 12 years of formal education. The MoCA is generally considered more sensitive to early or mild cognitive changes, which is why many clinics now prefer it as a first-line screen.
These tests can flag a problem, but they can’t tell you what’s causing it. A low score triggers deeper investigation.
The Neurological Exam
A doctor will perform a structured neurological exam that checks physical functions often affected by dementia. This includes testing reflexes, walking pattern, coordination (touching your finger to your nose, running your heel down your shin), eye movements, muscle strength, and sensory responses. The exam isn’t painful or invasive. It feels like a standard physical with extra attention to your nervous system.
Certain patterns point toward specific types of dementia. Asymmetrically brisk reflexes, reduced arm swing while walking, and jerky eye tracking movements are among the most common abnormal findings in Alzheimer’s disease. A tremor or changes in muscle tone can suggest dementia with Lewy bodies or Parkinson’s-related dementia. These physical signs, combined with cognitive test results, help narrow down the diagnosis.
Blood Tests to Rule Out Treatable Causes
Before diagnosing dementia, doctors need to make sure something reversible isn’t mimicking it. A surprising number of conditions can cause memory loss and confusion that looks like dementia but resolves with treatment. Standard blood work screens for vitamin B12 deficiency, thyroid problems (both overactive and underactive), and basic metabolic imbalances like abnormal calcium or blood sugar levels. Deficiencies in B1, B6, and folate can also impair cognition.
If there’s reason to suspect rarer causes, additional tests may check for liver or kidney dysfunction, copper levels (to rule out Wilson’s disease), vitamin E levels, or even heavy metal exposure from lead, arsenic, or mercury. Depression screening is also part of the standard workup, since severe depression can produce cognitive symptoms that closely resemble early dementia.
Brain Imaging
Most people undergoing a dementia evaluation will get at least one brain scan. The two main types serve different purposes.
A CT or MRI scan shows the brain’s structure. Doctors look for shrinkage in specific regions, particularly the hippocampus (the brain’s memory center), and check for evidence of strokes, tumors, fluid buildup, or other structural problems that could explain symptoms. MRI provides more detail than CT and is usually preferred when available.
A PET scan goes further by showing how active different brain regions are. In Alzheimer’s disease, a characteristic pattern emerges: reduced activity in the areas responsible for memory and spatial processing, particularly the hippocampus and the back portions of the brain near the top of the head. As the disease progresses, this reduced activity spreads forward toward the front of the brain. Other types of dementia show distinct patterns. Frontotemporal dementia primarily affects the front and front-side areas, while Lewy body dementia shows pronounced changes in the visual processing areas at the back of the brain. These differences help doctors distinguish one type of dementia from another.
Not everyone needs a PET scan. It’s more commonly ordered when the diagnosis is uncertain or when the clinical picture doesn’t fit neatly into one category.
Newer Blood Tests for Alzheimer’s
A significant development arrived in 2025 when the FDA cleared the first blood test to help diagnose Alzheimer’s disease. The test measures the ratio of two proteins in blood plasma: p-tau217 and beta-amyloid 1-42. These proteins are linked to the amyloid plaques that build up in the brains of people with Alzheimer’s.
In the clinical study that led to FDA clearance, 91.7% of people who tested positive on the blood test were confirmed to have amyloid plaques by PET scan or spinal fluid testing. Among those who tested negative, 97.3% were confirmed negative. The test is approved for adults 55 and older who are already showing cognitive symptoms. It’s not a standalone diagnostic tool or a screening test for people without symptoms, but it can reduce the need for more invasive or expensive testing like PET scans or spinal taps.
Spinal Fluid Analysis
In some cases, doctors collect a sample of cerebrospinal fluid through a lumbar puncture (spinal tap) to measure proteins directly associated with Alzheimer’s. The key measurement is the ratio of two forms of amyloid protein. An abnormal ratio indicates that amyloid plaques are accumulating in the brain. Tau protein levels in spinal fluid provide additional information about the extent of nerve cell damage.
This test is highly accurate but more invasive than blood work or imaging, so it’s typically reserved for cases where other results are inconclusive or when a precise biological confirmation is needed, such as before starting certain Alzheimer’s medications.
What the Full Process Looks Like
A comprehensive dementia evaluation usually begins with an initial appointment where the doctor reviews symptoms with you and, ideally, someone who knows you well, such as a spouse or adult child. That outside perspective matters because people with cognitive decline often don’t recognize the full extent of their own changes. The doctor will do the cognitive screening and neurological exam during this visit and order blood work and imaging.
Follow-up visits review results and may include more detailed neuropsychological testing, which involves a longer battery of tasks (often several hours) that map specific strengths and weaknesses across memory, language, problem-solving, and attention. At a specialized center like a university memory clinic, the evaluation team typically includes neurologists, neuropsychologists, and nurses who meet together to discuss findings before presenting a diagnosis to the patient and family.
In some cases, a diagnosis is deferred until all test results are in or until a repeat evaluation months later can determine whether symptoms are stable or progressing. That waiting period can be frustrating, but it reflects the reality that early cognitive changes sometimes need time to declare themselves clearly enough for an accurate diagnosis.