How Alzheimer’s Disease Is Diagnosed

Elderly woman sitting alone and looking sadly outside the window


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Diagnosing Alzheimer’s disease can involve several tests and scans. There is no simple or reliable way to diagnose this condition. 

In fact, Alzheimer’s disease can be definitively diagnosed only after death by performing an autopsy and studying the brain's tissues microscopically. As of now, healthcare providers can only determine whether Alzheimer’s is a possibility or probability.

Your healthcare provider will probably review your symptoms and medical history and then conduct a physical and neurological exam. They may also perform a series of tests to help determine whether you have symptoms like confusion, memory loss, or difficulty with reasoning or concentration.

You may undergo imaging scans and lab tests to help rule out other conditions. Your doctor may also suggest a spinal tap procedure to check for indicators of Alzheimer’s disease.

In addition to reviewing your symptoms and medical history, your healthcare provider may also ask close family members about your behavior and mental state. 

Self-Checks/At-Home Testing

The Self-Administered Gerocognitive Exam (SAGE), developed by the Wexner Medical Center at Ohio State University, is a test you can take at home if you have been experiencing cognitive difficulties, like trouble remembering, focusing, planning, or dealing with numbers. 

While the SAGE test cannot diagnose a specific health condition, like Alzheimer’s disease, it can help screen for mild cognitive impairment (MCI). MCI can be an early warning sign of Alzheimer’s disease or other conditions that can cause dementia. However, everyone who has MCI does not necessarily develop Alzheimer’s or dementia. 

You can download the SAGE test, print it out, and fill out your answers using a pen and paper. There is no time limit; however, it typically takes approximately 10 to 15 minutes to complete. You will need to answer all questions without the help of friends or family.

When you're done, take your answer sheet to your healthcare provider. They may suggest further tests based on your results. 

Alternatively, if your results suggest you don’t require any further testing at the moment, they may keep it on file as a baseline for the future. If you’re having memory problems, you may need to see your doctor every six to 12 months for a checkup.

Tests and Scales

If your primary care doctor thinks you might have Alzheimer’s disease, they may refer you to a specialist, like a neurologist or a geriatrician, for a diagnosis. Neurologists specialize in conditions that affect the brain and nervous system, whereas geriatricians specialize in the care of older persons. 

The doctor will likely review your symptoms and medical history, perform a physical and neurological exam, and order some scans and lab tests. 

Symptoms and Medical History

Your doctor will ask you what symptoms you are experiencing, how long you have had them, how severe they are, and whether they interfere with your ability to go about your daily routine.

Your doctor will also ask for a detailed medical history that may include information about:

  • Medications you are currently taking or have previously taken
  • Previous illnesses, surgeries, and procedures
  • Family medical history
  • Diet and lifestyle

This can help your doctor evaluate risk factors that might predispose you to Alzheimer’s. It can also help identify medications or illnesses that can cause symptoms similar to those of Alzheimer’s.

Physical and Neurological Examination

Your doctor will check your vital signs, like heart rate, blood pressure, pulse rate, and temperature. A neurological exam can include tests to check your reflexes, balance, coordination, speech, sight, and hearing.

Your doctor may also do a series of tests to evaluate your cognitive abilities and brain function. These tests may feel like a series of puzzles or games that are designed to test your:

These tests can help your doctor determine whether it’s safe for you to live independently, manage your finances, or drive a vehicle.

If you are diagnosed with Alzheimer’s, you may need to do these tests periodically to evaluate the condition's progression. 

Over the course of your appointment, your doctor will also evaluate your behavior as well as your mental and emotional state. On subsequent visits, they will make a note of any changes in your personality or behavior.

Lab Tests

You will probably be required to do routine lab tests, like blood and urine tests, to check your vitamin and mineral levels, blood counts, immune status, thyroid, kidney, and liver function. 

These tests can help rule out other health conditions that could be responsible for your symptoms. They can also help identify any other conditions, or comorbidities, that you may have, in addition to Alzheimer’s disease.

Imaging Scans

Imaging scans can help reveal any changes in your brain that Alzheimer’s disease has caused. This disease causes the brain to atrophy, or shrink. It can also cause abnormal clumps and tangled fibers in the brain. These clumps are known as amyloid plaques, and the tangles are referred to as neurofibrillary tangles, or tau.

Imaging scans also help rule out other health conditions that can cause similar symptoms. 

These are some of the imaging scans that you may need to do:

  • Computed tomography (CT): A CT scan can show changes in the brain's structure that are caused by Alzheimer’s disease, particularly in the late stages. These changes can include shrinkage and indentations in brain tissue.
  • Magnetic resonance imaging (MRI): An MRI scan can also reveal brain atrophy. Additionally, it can help identify other conditions, like tumors, stroke, and fluid buildup in the brain, that can cause symptoms similar to those of Alzheimer’s disease.
  • Functional magnetic resonance imaging (fMRI): An fMRI scan can help measure changes in blood flow to specific areas of the brain, which can help determine brain activity levels. fMRI scans can be used to evaluate how the brain changes with each stage of Alzheimer’s disease.
  • Amyloid positron emission tomography (PET): An amyloid PET scan can help reveal the buildup of amyloid protein in the brain.
  • Fluorodeoxyglucose positron emission tomography (FDG PET): An FDG PET scan can show how efficiently the brain can absorb glucose. Reduced glucose absorption can indicate Alzheimer’s disease.

Spinal Tap

Medically referred to as a “lumbar puncture,” a spinal tap procedure can check for amyloid and tau proteins that cause the plaques and tangles in the brain. These proteins are considered biomarkers of Alzheimer’s disease because if they are present in certain quantities, they can be an indicator of Alzheimer’s.

The spinal tap procedure involves using a thin needle to extract a small amount of fluid from your spine, known as cerebrospinal fluid. You will need to lie on your side for the procedure, and you will be given local anesthesia. You can take an over-the-counter painkiller like Tylenol afterward if you experience any discomfort.

A lumbar puncture procedure can diagnose other conditions like multiple sclerosis and meningitis; however, it is not the norm for diagnosing Alzheimer’s disease, as it is an invasive procedure.

Family Interviews

Your healthcare provider may talk to a friend or family member for information on your symptoms and behavior. 

Often, the initial symptoms of Alzheimer’s are mistaken for signs of aging. They gradually start becoming apparent to you and your close friends and family. 

Your loved ones will be able to tell your healthcare provider if they have witnessed any changes in your behavior or personality. They will also be able to report any difficulties you have with daily tasks, like cooking or getting dressed, for example. 

Additionally, they can convey information about your medication and medical history if you cannot do so because of your condition.

Diagnosing Alzheimer’s Disease

Your doctor will consider your symptoms, medical history, cognitive abilities, tests, and scans while arriving at a diagnosis. 

While it is not possible to conclusively diagnose Alzheimer’s while you are alive, your doctor will determine whether you have:

  • Possible Alzheimer’s dementia, which means there is a possibility that the dementia, or cognitive decline, you are experiencing could be caused by something else
  • Probable Alzheimer’s dementia, which means that there is no indication that the dementia you are experiencing is caused by anything else

Diagnosing Alzheimer’s early is difficult; however, catching this disease sooner can give you time to get your affairs in order. Alzheimer’s is a condition that gets progressively worse and has no cure, so you can also plan for your care. This can involve building a support network, making living arrangements, and identifying caregivers

How It All Fits Together

Diagnosing Alzheimer’s disease involves taking into account several factors.

For instance, education level can influence a person’s performance on cognitive tests. A person who cannot read or write very well may have a lower score but may not necessarily have Alzheimer’s disease. 

Similarly, brain scans alone cannot be relied on for diagnosis because some of the changes in the brain caused by Alzheimer’s overlap with the changes that occur over the normal course of aging. 

Genetic testing may sometimes be involved because early-onset Alzheimer’s can be inherited. 

Because of the complexity involved in diagnosing and managing Alzheimer’s, the process generally requires specialists. Depending on the hospital or clinic you go to for treatment, a psychiatrist or psychologist may also be involved in your care.

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3 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute on Aging. Alzheimer’s disease fact sheet.

  2. Scharre DW, Chang SI, Nagaraja HN, Vrettos NE, Bornstein RA. Digitally translated Self-Administered Gerocognitive Examination (Esage): relationship with its validated paper version, neuropsychological evaluations, and clinical assessments. Alzheimers Res Ther. 2017;9:44. doi:10.1186/s13195-017-0269-3

  3. Menéndez-González M. Routine lumbar puncture for the early diagnosis of Alzheimer’s disease. Is it safe? Front Aging Neurosci. 2014;6:65. doi:10.3389/fnagi.2014.00065

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