This includes the following for AD

Alzheimer disease is the most common cause of dementia, however there are many disorders that can cause or simulate dementia. To appropriately diagnose for AD, other forms of dementia or diseases need to be ruled out. This includes the following:

§  Medication-induced dementia. Medication-induced dementia is the most frequent cause of “reversible” dementia. To rule out a medication-induced dementia, a thorough drug history and a review of all current medication (both prescription and over-the-counter) needs be undertaken.

§  Metabolic/endocrine/nutritional/systemic disorders.  Metabolic/endocrine/nutritional/
systemic disorders (e.g., hypothyroidism, B12 deficiency, and systemic infections) are additional causes of “reversible” dementias and can be diagnosed with routine laboratory tests. Tests recommended include blood count, sedimentation rate (if indicated), electrolytes (including calcium), liver and renal function tests, urinalysis, syphilis serology, B12 levels, thyroid function tests, and a toxicity screen (if medical history and the physical exam so indicate).

§  Vascular dementia/hydrocephalus /tumors/hematoma. Vascular dementia (VaD) may result as a sequel to any form of cerebrovascular disease. VaD is responsible for approximately 20 percent of dementia cases and can Alzheimer disease.

§  Normal pressure hydrocephalus, brain tumors, and subdural hematoma, the most common of the structural brain lesions, and stroke can also present with dementia. Confirmation or exclusion of their presence usually requires a CT or MRI scan.

§  Depression. Depression is another common cause of dementia in the elderly population. The following symptoms cognitive impairment symptoms may be present: confusion, memory disturbance, and attention deficits, all of which can be mistaken for dementia. Depression may also coexist with dementia and exacerbate the problem, causing; “excess disability.” A good history and thorough mental-status is required as part of the treatment plan. The DSM-IV criterion for diagnosis of depression is often referred to confirm or rule out depression.