The way Alzheimer's is diagnosed is by ruling out other forms of dementia, or other diseases. There is not a direct test for Alzheimer's, which makes sense, bec

The way Alzheimer's is diagnosed is by ruling out other forms of dementia, or other diseases. There is not a direct test for Alzheimer's, which makes sense, because we don't really know what it is, Correction here: while other tests are sometimes given to rule out additional factors, there is an authoritative, direct test for Alzheimer's: clinically detectable cognitive impairment in combination with amyloid and tau pathology (as seen in cerebrospinal fluid or PET scan). This amyloid-tau copathology is basically definitional to the disease, even if there are other hypotheses as to its cause.