How Is Dementia Diagnosed?

Doctors diagnose dementia and Alzheimer’s disease through a series of steps that include a thorough medical evaluation, tests to assess mental status and mood, imaging of the brain, and laboratory tests. According to Stanford Health Care, the evaluation usually includes the following:

• A thorough medical history, including a review of past illnesses, current symptoms, medication use, diet and alcohol use. The doctor may also ask about any family history of Alzheimer’s disease or dementia. In some cases, the doctor may speak with family members to get some background on behavioral or cognitive changes they may have seen. 
• A physical exam
• Depression screening, since the symptoms of depression can often mimic those of dementia
• Memory testing, in which the doctor asks the person simple questions, such as the date or who the president is. The person may also be asked to memorize a short list of words or participate in problem-solving tasks.
• Neurocognitive testing to evaluate mental status more extensively. This may include a series of tests that evaluate judgment, attention, executive function and language skills.
• Imaging studies, which may include the following:
  • A computerized tomography (CT) scan and magnetic resonance imaging (MRI). These tests can reveal shrinkage in the brain as well as any underlying conditions that may be causing the person’s symptoms, such as a brain tumor, an aneurysm or a stroke.
  • A positron emission tomography (PET) scan and single photon emission computed topography (SPECT) scan. These very sophisticated imaging studies can show how the brain is functioning and reveal discrete structural changes such as the buildup of tau proteins seen in Alzheimer’s disease. 
• Blood and urine tests to look for metabolic abnormalities, such as a thyroid hormone or vitamin deficiency, infection or liver or kidney disease. Depending on the patient’s history, the doctor may do blood tests for HIV, toxic substances such as lead and medications that could lead to an altered mental state. 

• Lumbar puncture (spinal tap) to obtain cerebrospinal fluid for testing
• An electroencephalogram (EEG) to measure electrical activity in the brain, which can help distinguish between dementia and delirium and the specific abnormalities seen in the rare disorder Creutzfeldt-Jakob disease

Sources

“Dementia Diagnosis”. Stanford Medicine. https://stanfordhealthcare.org/medical-conditions/brain-and-nerves/dementia/diagnosis.html 

“Classic Creutzfeldt-Jakob Disease”. U.S. Centers for Disease Control and Prevention. https://www.cdc.gov/creutzfeldt-jakob/about/?CDC_AAref_Val=https://www.cdc.gov/prions/cjd/index.html