Brief Answer:
Several tests as follows.

Detailed Answer:
Hello and welcome to HealthcareMagic.

First step when evaluating Lazheimer's is neuropsychological testing, sort of questionnaires addressing different cognitive functions administered by neuropsychologists usually. They are necessary to determine if there is a real impairment of cognitive functions and if yes which areas are more affected (as that will orient the diagnosis on whether it's Alzheimer's or other types of dementia).

Afterwards brain imaging with preferably MRI and some routine blood tests including thyroid function and vitamin B12 levels are the standard tests. They are done to exclude other causes such as tumor, stroke, hydrocephalus, thyroid or vitamin B12 deficiency which can all cause dementia. The MRI might also show some changes in the brain in certain areas which would support Alzheimer's but it's not diagnostic, only enforces the diagnosis.

Whether to have other tests at this point depends on the patient and the center where he's evaluated. If all findings fit, in most centers no more tests are done. However in some major research hospitals or when findings are inconclusive suspecting other types of dementia, some more specialized tests may be done such as lumbar puncture (to check for cerebrospinal fluid levels of protein tau and amyloid) and PET scan may be done.

I remain at your disposal for other questions.

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