Blood Tests Used for the Diagnosis of Alzheimer's Disease

Blood tests are often used to rule out other conditions when diagnosing Alzheimer's
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Although science is getting closer, there's still no simple diagnostic test for Alzheimer's disease. Instead, physicians who suspect the condition basically start by ruling out other causes of the symptoms, which include memory loss, confusion, and problems with executive functioning.

This diagnostic process almost always includes blood testing for everything from infections to vitamin deficiencies. The goal is to uncover other possible conditions that might be causing or worsening the symptoms.

Blood Tests Used for Diagnosing Alzheimer's Disease

Although there are numerous tests, physicians generally request them all at once, so you don't need to worry about going through repeated blood draws and needle pricks. Different physicians may prefer different tests, and which ones are ordered depends on your medical history and other physical symptoms. Don't worry if one listed here wasn't ordered. If you have questions, don't be afraid to talk to your doctor about the results or how he or she interprets them.

Thyroid Functioning: This test evaluates thyroid functioning. Hypothyroidism (an underactive thyroid) can cause forgetfulness and fatigue. A thyroid disorder is treatable under the care of a physician.

White Blood Cell Count: Increased white blood cell counts can indicate infection. In rare cases, a bacterial or viral infection can reach the brain, causing symptoms similar to Alzheimer's disease.

Red Blood Cell Count: Low levels of red blood cells suggest anemia (iron deficiency). Symptoms of anemia include weakness, forgetfulness, mental confusion and loss of sex drive.

Screening Tests for Syphilis AntibodiesSyphilis, a sexually transmitted disease, can cause mental confusion if left untreated.

Kidney Function Screening: Poor kidney function means more waste products in the blood. It can produce disorientation, confusion, and difficulty expressing simple thoughts.

HIV Testing: HIV is a virus that can result in forgetfulness and mental confusion.

Erythrocyte Sedimentation Rate (ESR): Erythrocyte is another term for a red blood cell. The test measures how quickly red blood cells settle to the bottom of a thin tube containing the blood sample. Higher measurements could reflect various things, including inflammation, infection or some other disorder (such as cancer or an autoimmune disease), or even a pregnancy.

Serum Glutamic Pyruvic Transaminase (SGPT) Testing: SGPT is an enzyme concentrated in the liver. If the liver is damaged, high levels of this enzyme will be found in the blood. This may indicate problems with the liver's ability to detoxify the blood, which could impair brain functioning.

Toxic Screening: As its name suggests, this test measures toxic substances in the blood -- anything from street drugs to excessive levels of prescription medications. The test helps physicians determine if a medication or drug might be causing dementia symptoms.

Is It a True Diagnostic Test?

Multiple researchers have been working to develop a blood test that will both diagnose Alzheimer's disease accurately, as well as predict Alzheimer's possibly years before symptoms develop. For example, one study was published in 2014 that reported a 90% accuracy rate in predicting the development of mild cognitive impairment or Alzheimer's for participants over the next two to three years.

Although more research is needed before any such test will be available for general use, an effective diagnostic test could revolutionize not only the diagnosis of Alzheimer's disease, but potentially its treatment as well. This could allow the disease to be recognized before any cognitive damage has occurred.​

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