While examining the brain after death is the most definitive way to diagnose Alzheimer's disease, a physician experienced in cognitive evaluations using validated clinical criteria can diagnose Alzheimer's during life with more than 90 percent accuracy. Because there is no simple or single test available to diagnose the Alzheimer's, the disease sometimes goes unrecognized and misdiagnosed in primary care settings.An evaluation for Alzheimer's disease includes a history and examination, assessment of cognitive abilities, blood tests and brain scans. The physician will need to get information from the patient and also individuals (often family members) who know and have observed the patient.