Diagnosing Alzheimer's: How Alzheimer's is diagnosed

To diagnose Alzheimer's dementia, healthcare professionals conduct tests to measure memory impairment and other thinking skills. They also judge functional abilities and identify behavior changes. A series of tests can rule out other possible causes of symptoms.

By Mayo Clinic Staff

Alzheimer's dementia can be diagnosed in several different ways. Often, Alzheimer's is diagnosed through an exam by a member of your healthcare team. The healthcare professional evaluates your symptoms and may order several tests. The health professional may talk to your friends and family members to find out more about your symptoms and behavior.

It's important to get an accurate diagnosis of Alzheimer's, the most common type of dementia. The correct diagnosis is an important first step toward getting the appropriate treatment, care, family education and plans for the future.

Early symptoms of Alzheimer's dementia

Early symptoms of Alzheimer's dementia include:

  • Memory impairment, such as trouble remembering events.
  • Having a hard time concentrating, planning or problem-solving.
  • Trouble finishing daily tasks at home or at work, such as writing or using eating utensils.
  • Confusion with location or passage of time.
  • Having visual or spacial issues, such as not understanding distance in driving, getting lost or misplacing items.
  • Trouble with language, such as not being able to find the right word or having a reduced vocabulary in speech or writing.
  • Using poor judgment in decisions.
  • Withdrawal from work events or social engagements.
  • Changes in mood, such as depression or other behavior and personality changes.

Alzheimer's dementia can affect several aspects of your daily life.

When warning signs of Alzheimer's dementia appear, it's important that you get a prompt and accurate diagnosis.

Diagnosing Alzheimer's dementia

To diagnose Alzheimer's dementia, you might see your healthcare professional. Or you might see a doctor trained in brain conditions, known as a neurologist, or a doctor trained to treat older adults, known as a geriatrician. The doctor or other healthcare professional reviews your symptoms, medical history and medicine history. Your health professional may interview someone who knows you well, such as a close friend or family member. You'll also have a physical exam and several tests.

During your appointment, your healthcare professional looks at:

  • Whether you have impaired memory or thinking skills, also known as cognitive skills.
  • Whether you exhibit changes in personality or behaviors.
  • The degree of your memory or thinking impairment or changes.
  • How thinking impairment affects your ability to function in daily life.
  • The cause of your symptoms.

You may need lab tests, brain-imaging tests or detailed memory testing. These tests can provide useful information for a diagnosis. They also can rule out other conditions that cause similar symptoms.

Ruling out other conditions

Doctors and other healthcare professionals give you a physical exam and check that you don't have other health conditions that could be causing or contributing to your symptoms. They may look for signs of past strokes, Parkinson's disease, depression, sleep apnea or other medical conditions.

Testing memory loss and other symptoms

Your healthcare professional may ask you to answer questions or perform tasks that measure your cognitive skills. The tasks help to evaluate your memory, abstract thinking, problem-solving, language usage and related skills.

  • Mental status testing. This test focuses on your thinking skills, known as cognitive skills, and memory. The scores on these tests can reveal the degree of cognitive impairment.
  • Neuropsychological tests. You may see a specialist trained in brain conditions and mental health conditions, known as a neuropsychologist. This specialist can do extensive tests of your memory and cognitive skills.

    The tests help your doctor and other healthcare professionals determine if you have dementia. They help your healthcare team know if you're able to safely complete daily tasks, such as taking medicines as scheduled and managing your finances. These tests also provide information on what you can still do as well as what you may have lost. And they can tell your healthcare professional if depression may be causing your symptoms.

  • Interviews with friends and family. Doctors and other healthcare professionals may ask your family members or friends questions about you and your behavior.

    Healthcare professionals look for details that don't fit with your former level of function. Family members or friends often can explain how your cognitive skills, functional abilities and behaviors have changed over time.

These tests, the physical exam, and information on age and duration of worsening symptoms often are enough to diagnose Alzheimer's dementia. However, when the diagnosis isn't clear, healthcare professionals may need to order additional tests.

Laboratory tests

You may need lab tests to rule out other conditions that cause symptoms similar to Alzheimer's dementia. For example, you might be tested for a thyroid condition or not having enough vitamin B-12 in the body.

A cerebrospinal fluid test may be recommended to help diagnose Alzheimer's. Amyloid and tau proteins can be measured in the fluid. The ratio of these proteins can help determine if you have Alzheimer's dementia. Most of the time, a cerebrospinal fluid test is not necessary for a diagnosis. But the test may be useful in some instances or if symptoms are rapidly getting worse.

Brain imaging tests

Alzheimer's dementia results from the loss of brain cells over time. This is known as degeneration. Degeneration may appear in a variety of ways in brain scans.

However, these scans alone aren't enough to make a diagnosis. Scans aren't used to diagnose Alzheimer's dementia because there is overlap in what is considered typical age-related change in the brain and change related to Alzheimer's.

However, brain imaging can help:

  • Rule out other causes, such as heavy bleeding, brain tumors or strokes.
  • Distinguish between different types of degenerative brain disease.
  • Establish a baseline about the degree of degeneration.

The brain-imaging technologies most often used are:

  • Magnetic resonance imaging (MRI). An MRI uses powerful radio waves and magnets to create a detailed view of your brain.
  • Computerized tomography (CT). A CT scan uses X-rays to obtain cross-sectional images of your brain.
  • Positron emission tomography (PET). A PET scan uses a radioactive substance known as a tracer to detect substances in the body. There are different types of PET scans. The most commonly used PET scan is a fluorodeoxyglucose (FDG) PET scan. This scan can identify brain regions with decreased glucose metabolism. The pattern of metabolism change can distinguish between different types of degenerative brain disease.

    PET scans have recently been developed that detect clusters of amyloid proteins, known as plaques, or tau, known as neurofibrillary tangles. Both are associated with Alzheimer's dementia. These types of PET scans are typically used in the research setting.

Future of diagnosis

Researchers are working on new ways to diagnose Alzheimer's dementia earlier. New tests might be able to diagnose the disease when symptoms are very mild or even before symptoms start. Currently, researchers are developing tests that measure amyloid or tau in the blood. These tests are promising and may be used to pinpoint who is at risk of Alzheimer's dementia, and whether Alzheimer's is the cause of dementia.

Scientists are investigating several disease markers and diagnostic tests. These biomarkers include genes and proteins, including tau, related to Alzheimer's. New imaging tests also are being developed. These may help indicate whether you have Alzheimer's dementia and how much the disease has progressed. However, more research on these tests is necessary.

Benefit of an early diagnosis

Some people feel nervous about seeing a healthcare professional when they or a family member has memory issues. Some people hide their symptoms, or family members cover for them. It can be hard to deal with the losses that Alzheimer's dementia can bring, such as losing independence and the ability to drive.

While there's no cure for Alzheimer's, an early diagnosis can still be helpful. Knowing what you can do is just as important as knowing what you can't do. If another treatable condition is causing memory loss, your healthcare team can start treatments.

For those with Alzheimer's dementia, starting medicines early can help slow the decline in memory and other cognitive skills. Other medicines and interventions can help manage symptoms. You also may be able to participate in clinical trials.

You and your caregivers can learn strategies to manage your changes in skills and to reduce how Alzheimer's dementia affects everyday life. Strategies include learning how to make your home safer, establish routines and plan activities.

An early diagnosis also helps you, your family and caregivers plan for the future. You'll have the chance to make informed decisions on a number of issues, such as:

  • Appropriate community services and resources.
  • Options for residential and at-home care.
  • Plans for handling financial issues.
  • Expectations for future care and medical decisions.

When healthcare professionals diagnose you or a family member with Alzheimer's, they can help you understand the disease. They can answer your questions and explain what to expect. Your healthcare team can help you figure out ways to maintain independence, health and safety.

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.

March 13, 2024 See more In-depth

See also

  1. Alzheimer's sleep problems
  2. Alzheimer's: New treatments
  3. Alzheimer's 101
  4. Understanding the difference between dementia types
  5. Alzheimer's disease
  6. Alzheimer's genes
  7. Alzheimer's drugs
  8. Alzheimer's prevention: Does it exist?
  9. Alzheimer's stages
  10. Antidepressant withdrawal: Is there such a thing?
  11. Antidepressants and alcohol: What's the concern?
  12. Antidepressants and weight gain: What causes it?
  13. Antidepressants: Can they stop working?
  14. Antidepressants: Side effects
  15. Antidepressants: Selecting one that's right for you
  16. Antidepressants: Which cause the fewest sexual side effects?
  17. Anxiety disorders
  18. Atypical antidepressants
  19. Caregiver stress
  20. Clinical depression: What does that mean?
  21. Corticobasal degeneration (corticobasal syndrome)
  22. CT scan
  23. Depression and anxiety: Can I have both?
  24. Depression, anxiety and exercise
  25. What is depression? A Mayo Clinic expert explains.
  26. Depression in women: Understanding the gender gap
  27. Depression (major depressive disorder)
  28. Depression: Supporting a family member or friend
  29. Did the definition of Alzheimer's disease change?
  30. How your brain works
  31. Intermittent fasting
  32. Lecanemab for Alzheimer's disease
  33. Male depression: Understanding the issues
  34. MAOIs and diet: Is it necessary to restrict tyramine?
  35. Marijuana and depression
  36. Mayo Clinic Minute: 3 tips to reduce your risk of Alzheimer's disease
  37. Mayo Clinic Minute: Alzheimer's disease risk and lifestyle
  38. Mayo Clinic Minute: New definition of Alzheimer's changes
  39. Mayo Clinic Minute: Women and Alzheimer's Disease
  40. Memory loss: When to seek help
  41. Monoamine oxidase inhibitors (MAOIs)
  42. MRI
  43. Natural remedies for depression: Are they effective?
  44. Nervous breakdown: What does it mean?
  45. New Alzheimers Research
  46. Pain and depression: Is there a link?
  47. Phantosmia: What causes olfactory hallucinations?
  48. Positron emission tomography scan
  49. Posterior cortical atrophy
  50. Seeing inside the heart with MRI
  51. Selective serotonin reuptake inhibitors (SSRIs)
  52. Serotonin and norepinephrine reuptake inhibitors (SNRIs)
  53. Sundowning: Late-day confusion
  54. Treatment-resistant depression
  55. Tricyclic antidepressants and tetracyclic antidepressants
  56. Video: Alzheimer's drug shows early promise
  57. MRI
  58. Vitamin B-12 and depression
  59. Young-onset Alzheimer's