There are no definitive imaging or laboratory tests for the diagnosis of Alzheimer's disease while the patient is alive. Definitive diagnosis is made by an autopsy of the brain, which occurs after the patient's death. The autopsy will reveal brain changes that include neurofibrillary tangles and neuritic plaques. While the patient is alive, tests can assist with diagnosis. At most Alzheimer's specialty clinics, the diagnosis of Alzheimer's disease is correct over 90% of the time.