How Does the Doctor Test for Alzheimer’s Disease?
What Is Alzheimer’s Disease?
When a person has Alzheimer’s disease (AD), cells in certain parts of the brain die and the connections between brain cells disappear. Memory and other brain functions suffer.
Scientists have yet to identify the exact causes of AD. We do know that the risk of developing AD increases greatly after age 65, according to the Mayo Clinic. Currently there is no cure for the disease. However, treatments can help with some symptoms.
Symptoms of Alzheimer’s Disease
The first signs of Alzheimer’s disease are moments of forgetfulness or confusion. Someone with AD may have trouble remembering something that they recently learned.
In early AD, it may be difficult to organize your thoughts. A person with early AD usually is aware of these changes, but sometimes family members notice them first. Frequent episodes of forgetfulness or confusion should prompt a visit to the doctor.
Mini-Mental State Exam
One of the first tests a doctor might perform to diagnose AD is called a mini-mental state exam (MMSE). The doctor will ask the patient to:
- answer questions such as what is the current date and location of the doctor’s office
- identify objects in the room
- recall a short list of words presented at the beginning of the exam
The top score on an MMSE is 30. A score of 12 or lower suggests severe dementia and the likelihood of AD, according to the Alzheimer's Association.
The mini-cog is another simple written test that evaluates a person’s brain function. This test has two parts. In the first part, the patient is given a list of three common objects. Several minutes later, the doctor asks them to repeat the list.
For the second part, the doctor asks the patient to draw a clockface with the numbers one to 12 in their correct places. The test taker is then asked to draw hands on the clock to show the time selected by the examiner.
Your doctor will need your complete medical history to diagnose AD. They’ll also want to know if anyone in your family has AD or other types of dementia.
An AD screening also requires a physical examination that includes checking your blood pressure and other health information. You’ll need to tell the doctor about the medications you take and answer questions about your alcohol use, diet, and exercise.
Testing for AD includes an evaluation of your brain and nervous system. That means the doctor will check your reflexes, eye movement, and speech. They’ll also look for signs of brain injury, stroke, and conditions such as Parkinson’s disease.
Your doctor will want to rule out all other illnesses that affect brain health before making a diagnosis of AD.
MRI and CT
One way a doctor can eliminate other causes of Alzheimer’s symptoms is through brain imaging. Computerized tomography (CT) scans and magnetic resonance imaging (MRI) give doctors a good look at the brain. These tests can’t definitively diagnose AD, but they can help a doctor see if a tumor or another condition is causing memory or thinking problems.
It’s helpful for doctors to observe brain activity because people with AD have less brain cell activity in certain parts of the brain. This can be done with a brain imaging technology called positron emission tomography (PET).
One type of PET measures how much blood sugar is used by brain cells. Brain cells affected by AD use less blood sugar.
Scans that look for specific molecules in the brain are among the newer tests for AD. A special compound that’s injected into a patient travels to the brain where it detects molecules that show AD may be developing.
The Alzheimer's Association reports that molecular imaging may one day help doctors determine how the disease is progressing. It also could aid in delivering medications to the right locations in the brain.
Doctors are learning more about biomarkers, genes or chemicals in a person’s body fluids that signal the presence of a disease. Biomarkers of certain proteins in brain and spinal fluid, called tau and beta-amyloid, may be especially helpful in diagnosing AD. Doctors can sample that fluid by doing a spinal tap procedure.
- Alzheimer’s disease risk factors. (2013). Mayo Clinic. Retrieved November 13, 2013, from http://www.mayoclinic.com/health/alzheimers disease/DS00161/DSECTION=risk-factors
- Alzheimer’s and Dementia Testing for Earlier Diagnosis. (2013). Alzheimer’s Association. Retrieved Nov. 12, 2013, from http://www.alz.org/research/science/earlier_alzheimers_diagnosis.asp
- Diagnosing Alzheimer's: How Alzheimer's is diagnosed. (2013). Mayo Clinic. Retrieved Nov. 12, 2013, from http://www.mayoclinic.com/health/alzheimers/AZ00017
- About Alzheimer's Disease: Diagnosis. (2013) National Institute on Aging. Retrieved Nov. 12, 2013, from http://www.nia.nih.gov/alzheimers/topics/diagnosis
- Tests for Alzheimer's Disease and Dementia. (2013). Alzheimer’s Association. Retrieved Nov. 12, 2013, from http://www.alz.org/alzheimers_disease_steps_to_diagnosis.asp