Alzheimer's Disease Diagnosis
- What It Is
- Risk Factors
- Living With
- User Questions
- Alternative Treatment
- Care Guide
- Questions for Your Doctor
- When to Contact a Doctor
- Find a Doctor
- Resource Guide
How to Diagnose Alzheimer's Disease
There are no laboratory tests to confirm a diagnosis of Alzheimer's disease. However, your doctor will be able perform a thorough clinical evaluation and conduct tests that will provide a diagnosis with a 90% accuracy rate, and will rule out other potential conditions.
Initially, the doctor will ask about your symptoms and medical history, and perform a physical exam. Tests to rule out other conditions may include:
Blood and Urine Tests -This may be done to rule out other forms of dementia. These tests may include:
- Electrolytes (sodium, potassium, and calcium)
- Thyroid function tests
- Complete blood count (CBC)
- Levels of B vitamins
- Erythrocyte sedimentation rare (ESR)
- Lyme disease test
- HIV test
- Vasculitis work up
Neurological Exam -This exam tests the nervous system (brain, spinal cord, nerves, and muscles) for evidence of other neurological disorders.
Psychological Testing -Pyschological testing is used to rule out depression or other emotional illnesses that may often be the first sign of Alzheimer's disease.
Neuropsychological Evaluation -This evaluation tests language, memory, reasoning, judgment, and orientation, and may assist in the diagnosis of Alzheimer's disease in the early stage or indicate other causes of dementia.
Mental Status Testing -This testing is used to evaluate memory, sense of time and place, and problem-solving abilities, attention span, language skills, visual spatial perception, learning capacity, judgement, insight, and decision making skills. This is often a part of the Neurological examination and Neuropsychologic testing.
CT and MRI Scan-Your doctor may suggest tests, such as computed tomography (CT) or magnetic resonance imaging (MRI), which will take a picture of your brain. These scans may help to identify any abnormalities in the brain, which may indicate Alzheimer's disease or point to other causes of dementia.
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PET Scan - Positron emission tomography (PET) is a special type of brain imaging scan that involves use of special radioactive compounds. It is expensive and not widely available, but at times PET scans can provide valuable information that CT/MRI scans cannot provide. In addition, Medicare and other insurers will cover the cost of a PET scan in certain cases.
Though not routine, a lumbar puncture (spinal tap) to test the cerebrospinal fluid (CSF) and an ophthalmologic screening can be done to investigate for other atypical dementias. Additionally, EEG (electroencephalogram) is a test that measures and follows the electrical activity of the brain. This is not a routine test for dementia, but may be used in investigation and diagnosing atypical dementias.
A diagnosis of Alzheimer's disease usually falls into one of three categories:
Probable Alzheimer's -This indicates that other dementia-related disorders have been ruled out, and that the symptoms are likely due to Alzheimer's disease. This is based on the Mini Mental Status Exam, with at least 2 areas of cognition affected, worsening of memory, and impairment of activities of daily activities.
Possible Alzheimer's -The dementia is caused by Alzheimer's disease, but there may be other disorders present that may change the progression of the Alzheimer's disease in a manner that is somewhat atypical from just Alzheimer's disease.
Definite Alzheimer's -This diagnosis can only be made at the time of death through an autopsy, when a pathologist can study the brain tissue. This is the only way to diagnose the disease with complete certainty.