A definitive diagnosis of Alzheimer's disease (AD) requires histopathologic examination which is rarely done. Which tests will the nurse expect to be ordered to rule out other disorders?

Computed tomography (CT) scan
MRI of the brain
Positron emission tomography (PET) scan
Screening for vitamin B12 deficiency

Explanation

• While laboratory tests are not helpful in confirming a diagnosis of AD, some tests are indicated to exclude contributing secondary causes.

• The DSM-5 recommends MRI of the brain to rule out cerebrovascular disease, chronic subdural hematoma, cerebral neoplasm, and regional brain atrophy suggesting dementia.

• Positron emission tomography (PET) scan measures the metabolic activity of the cerebral cortex and may help confirm early diagnosis.

Computed tomography (CT) scan may show more brain atrophy than occurs in normal aging.

• Vitamin B12 deficiency can cause reversible memory and attention problems.

• Incorrect: Tensilon test confirms the diagnosis of myasthenia gravis.

• Incorrect: Oral cholecystography confirms the presence of gallstones.

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