How Is Alzheimer’s Disease Diagnosed?

Alzheimer’s disease (AD) is a progressive brain disease that causes a severe decline in a person’s cognitive (brain-related) abilities, such as thinking, memory, and judgment—making early diagnosis especially crucial in order to manage symptoms and improve one’s quality of life.

AD is most common among people over the age of 65 and is different from normal memory changes as you age. Unlike normal memory changes, symptoms of AD often interrupt daily life and make it difficult for someone with the condition to function independently. Because AD affects each person differently, there is no single test that can diagnose you or your loved one with the condition—therefore, a provider may use a variety of tests. 

If you begin to notice changes to your own memory or have a loved one or caregiver who is displaying symptoms of AD, it’s a good idea to visit a healthcare provider as soon as you can. During your appointment, you can expect a healthcare provider to take a thorough medical history, perform a physical exam and psychiatric evaluation, and order additional testing such as a neurological exam, blood tests, and imaging scans.

Going through testing for AD can seem scary—and it’s OK to feel that way. If you are experiencing memory changes, you may find it helpful to bring a loved one with you to your appointment. In contrast, if you have a loved one who may need testing, you may gently encourage them to bring you or another loved one to their appointment. 

Having support can help you or your loved one feel at ease during the appointment and help your provider learn more about any recent changes in thinking and behavior that others may be noticing. 

Medical History  

Before a healthcare provider can perform evaluations and order testing, it’s important for them to learn about your or your loved one’s medical history. During your initial appointment, your provider may ask the following questions:

• Does anyone in your family have a history of Alzheimer’s disease or dementia?
• Do you have a history of head injuries or brain trauma?
• Have you received a diagnosis for any other health conditions? 
• Are you having any trouble carrying out daily activities?
• Have you or your loved ones noticed any changes in your behavior?
• Do you misplace items, forget names, or have trouble remembering important tasks? 
• Are you experiencing any mood swings?
• Have you made any recent lifestyle changes? 
• Do you drink alcohol, smoke cigarettes, or use any recreational drugs?
• Are you taking any medications currently? 
• What do your sleeping and eating habits look like?

In some cases, a healthcare provider may also want to interview a loved one at the appointment to get their perspective about any cognitive, behavioral, or psychological changes before ordering additional tests.

Cognitive and Neurological Exams 

Cognitive and neurological testing (or, exams that check the brain and behavior) is the most reliable way for a provider to detect any changes in memory, thinking, and behavior. This type of testing is typically detailed and can take several hours or multiple appointments to complete. 

The goal of this testing is to learn more about your or your loved one’s cognitive (brain-related) abilities. A neurologist, psychiatrist, or psychologist will likely be conducting the exam. During neuropsychological testing, the provider can use a variety of tests to understand several brain functions. 

These functions may include:

• Memory and learning 
• Problem-solving
• Attention and concentration
• Using reason and logic
• Counting numbers 
• Language and communication
• Social functioning
• Emotions and mood 
• Motor (movement-related) functions 

In order to study these functions, your provider may use one or more of the following exams:

• Mini-Mental State Exam (MMSE): Checks for problems with thinking, learning, memory, and communication 
• Mini-Cog: A three-step test that asks you to repeat three words, draw a clock from memory, and then recall the three words from earlier 
• Functional Activities Questionnaire (FAQ): Measures your ability to carry out daily tasks such as making food, paying bills, or getting dressed 
• Montreal Cognitive Assessment (MoCA): An Alzheimer’s disease screening measure that looks assesses attention, memory, language, orientation, and critical thinking skills 
• 7-Minute Screen: A short examination that looks at four cognitive functions, including memory, orientation, visual-spatial skills, and verbal fluency 
• Neuropsychiatric Inventory Questionnaire (NPI-Q): A questionnaire that a caregiver or loved one fills out for the person who is undergoing testing—which includes questions about delusional behavior, hallucinations, depression, apathy, anxiety, and lifestyle habits 

There are several other exams and measures that a healthcare provider may use. Each exam has its own scoring guidelines and criteria. The results from these exams can help your or your loved one’s healthcare provider figure out the next steps and how to move forward with diagnosis or treatment.

Spinal Tap

A spinal tap (also called a lumbar puncture) is a procedure that removes a small amount of cerebrospinal fluid (CSF) for evaluation. CSF is a type of fluid in your brain and spinal cord that helps cushion your brain and spine from injury. To complete a spinal tap, a provider will use a needle to take a sample of fluid from your spine and send it in for testing.

In people with AD, the levels of certain proteins in the CSF are either too low or too high. These proteins are called “biomarkers”—which are measurable signs in the body that can signal a medical condition. Your CSF results can detect whether you have any biomarkers. CSF biomarkers are important for an AD diagnosis, but they don’t always lead to a definitive answer or diagnosis. 

That’s why research on CSF remains ongoing. In May 2022, the U.S. Food and Drug Administration (FDA) approved a new CSF test for Alzheimer’s disease. Researchers are now also studying how to find blood biomarkers—rather than taking a CSF sample—to look for biological signs of AD. There’s also a push to find blood biomarkers, which are easier to collect.

Keep in mind: not all hospitals offer this exam and not all health insurances cover the cost. If results of other diagnostic tests have not given you a definitive diagnosis and you think a spinal tap may be useful, talk to your provider and insurance company to see whether it’s feasible to get this testing done.

Brain Imaging

Imaging tests can also help look for structural changes in the brain. If your or your loved one’s provider considers imaging scans for testing, the main types of brain imaging tests include:

• Computed tomography (CT): Creates photos that can check for signs of stroke, brain bleeding, or tumors 
• Magnetic resonance imaging (MRI): Generates more detailed pictures than a CT scan but checks for similar concerns, such as stroke, bleeding, tumors, fluid retention, and head trauma 

It’s important to note that imaging tests alone cannot diagnose someone with Alzheimer’s disease. However, they can help rule out other conditions and give your provider more information about your brain’s structure. That’s why imaging tests are often done in combination with cognitive exams.

Lab Tests

While blood and urine tests won’t show if someone has AD, these exams can check for related conditions that could be causing your or your loved one’s symptoms. These tests can check for concerns such as infections, vitamin deficiencies, or other underlying conditions.

Screening for Related Conditions

Sometimes, symptoms of AD can mimic the symptoms of other conditions. During your or your loved one’s diagnostic process, a provider will likely screen for related conditions to rule out any underlying health issues.

Some conditions or situations that can cause similar symptoms of AD include:

• Traumatic brain injury 
• Mild cognitive impairment 
• Brain tumor or infection
• Concussion 
• Temporary amnesia (memory loss)
• Hydrocephalus (fluid in the brain)
• Lyme disease
• Epilepsy 
• Parkinson’s disease 
• Side effects of certain medications
• Vitamin B12 deficiency
• Thyroid disease
• Heavy alcohol or drug use 
• Depression 
• Anxiety 

If a healthcare provider suspects a different condition may be causing symptoms, they can order additional testing or refer you or your loved one to a specialist for diagnosis and treatment.