In Alzheimer’s disease, certain proteins are deposited in the brain, including beta amyloid protein and tau. The buildup of these two proteins leads to nerve injury and the symptoms of Alzheimer’s dementia.

It’s often hard to tell the difference between normal slips in recollection that occur as we age and the deeper lapses that could signal disease. One helpful test is the mini-mental state exam (MMSE), which tests a range of everyday mental skills. Neuroimaging, such as PET and MRI scans, can yield images of brain metabolism and show where nerve cells have died. Tests for changes in levels of amyloid beta protein and phospho-tau levels in the spinal fluid may increase the certainty of diagnosis at a time when treatments might be most effective.