Diagnosing Alzheimer's disease

Alzheimer's disease can be diagnosed in many ways. Often, it's diagnosed through an exam by a member of your healthcare team. The healthcare professional asks about your symptoms and may order several tests. The health professional may talk with 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 right plans in place for you. These include treatment, care, family education and plans for the future.

Early symptoms of Alzheimer's dementia include loss of thinking skills. This is called cognitive decline. It can show up as:

• Memory loss, such as trouble remembering events.
• Trouble with concentration, planning or problem-solving.
• Poor judgment with decision-making.

Early symptoms also may include changes in social behaviors or communication, such as:

• Withdrawal from work events or social engagements.
• Changes in mood, such as depression or other behavior and personality changes.
• Trouble with language, such as not being able to find the right word or using fewer words when speaking or writing.

Lastly, early symptoms can include loss of visual or spatial skills including:

• Trouble with routine tasks at home or at work, such as writing or using eating utensils.
• Confusion with location or passage of time.
• Not understanding distance in driving, getting lost or misplacing items.

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

When symptoms of Alzheimer's dementia appear, it's important that you get an accurate diagnosis right away.

To diagnose Alzheimer's dementia, you may see your regular healthcare professional. Or you may see a doctor trained in brain conditions, called a neurologist. A doctor trained to care for older adults, called a geriatrician, also may diagnose you. The 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 also have a physical exam and several tests.

During your appointment, your healthcare professional checks:

• If you show a loss of memory or thinking skills. These are called cognitive skills.
• If you show changes in personality or behaviors.
• The degree to which your memory, thinking, behavior or personality have changed.
• How loss of thinking skills 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 give useful information for a diagnosis. They also can rule out other conditions that cause similar symptoms.

A physical exam can help rule out other causes of your symptoms. They may look for signs of past strokes, Parkinson's disease, depression, sleep apnea or other medical conditions.

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

This test focuses on your thinking skills, called cognitive skills, and memory. The test scores can show the degree of cognitive decline.

You may see a specialist trained in brain conditions and mental health conditions called a neuropsychologist. This specialist can do a range of tests of your memory and thinking skills.

The tests help your doctor and other healthcare professionals decide if you have dementia. The tests help your healthcare team know if you can safely complete daily tasks, such as taking medicines and managing your finances. The tests also provide information on skills you can still do and skills you may have lost. And they can tell your healthcare team if depression may be causing your symptoms.

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 thinking skills, functional abilities and behaviors have changed over time.

These tests, the physical exam, your age and the length of time symptoms have been going on often are enough to diagnose Alzheimer's dementia. When the diagnosis isn't clear, your healthcare team may need to order more tests.

You may need lab tests to rule out other conditions that cause symptoms similar to Alzheimer's dementia. For example, you may have a thyroid test or a vitamin B-12 test.

If you have trouble with thinking and memory, your healthcare team may order blood tests to check for signs connected to Alzheimer's disease. These signs are called biomarkers.

One biomarker linked to Alzheimer's is a protein called tau, specifically p-tau217. Alzheimer's causes certain proteins to build up and form clusters in the brain. Clusters of misfolded proteins are known as amyloid plaques, and clusters of tau are known as neurofibrillary tangles.

When these Alzheimer's-related changes happen, they create high levels of p-tau217 in the blood. If your blood test shows high levels of p-tau217, it strongly suggests your cognitive decline is due to Alzheimer's disease. This test should not be done if you show no signs of cognitive decline, even if you have a family history of Alzheimer's.

Also, your cerebrospinal fluid may be tested to help diagnose Alzheimer's. Amyloid and tau proteins can be measured in the fluid. Levels of the protein abeta42 will be tested along with ratios between levels of protein. These ratios include how much abeta42 is in the fluid compared to abeta 40 and how much p-tau181 is in the fluid compared to abeta42.

Results from these tests are closely linked to Alzheimer's-related brain changes and how these changes show up on a brain-imaging test known as an amyloid-PET scan. Most of the time, a cerebrospinal fluid test is not needed for a diagnosis. But the test may be useful in some instances or if symptoms are quickly getting worse.

Alzheimer's dementia is caused by the loss of brain cells over time. This is known as degeneration. Degeneration may show up in many ways in brain scans.

But 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.

Brain imaging can help:

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

The brain-imaging technologies most often used are:

• MRI. An MRI uses powerful radio waves and magnets to create a detailed view of your brain.
• CT. A CT scan uses X-rays to obtain cross-sectional images of your brain.

• 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 used PET scan is a fluorodeoxyglucose (FDG) PET scan. This scan can show brain regions with lower glucose metabolism. The pattern of metabolism change can tell the difference between the types of degenerative brain disease.

  PET scans have recently been developed that show clusters of amyloid proteins, known as plaques, or tau, known as neurofibrillary tangles. Both types of clusters are connected with Alzheimer's dementia.

Researchers are working on new ways to diagnose Alzheimer's dementia earlier. Tests are being developed to diagnose Alzheimer's disease even before symptoms start.

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 help 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.