During my fellowship training in geriatric psychiatry back in the mid-90's, we were taught repeatedly that as long as you were thorough and followed the rules, it was fairly easily to make a diagnosis of Alzheimer's disease (AD) and have reasonable confidence you were right. In fact, I recall specifically being told that clinicians diagnose Alzheimer's disease with 90% accuracy. A little research today led me to one of the articles supporting that idea. As the authors from Johns Hopkins University pointed out back in 1996: "We conclude that the criteria of the National Institute of Neurological Disorders and Stroke/Alzheimer Disease and Related Disorders Association for possible or probable AD are highly accurate..."
15 years later, we clinicians are looking a lot dumber than we used to when it comes to diagnosing Alzheimer's disease. According to new research released Feb. 23, 2011, Alzheimer's disease was accurately diagnosed about half the time, a far cry from the old figure of 90%. The researchers autopsied the brains of 426 Japanese-American men who were residents of Hawaii, and 211 of them were diagnosed with dementia when they alive (mostly Alzheimer's disease). The men died at an average age of 87, and for the half who were misdiagnosed as having Alzheimer's disease, their brains had one or a combination of other brain lesions that explained their dementia. Some were found to actually have Dementia with Lewy Bodies.
So while larger studies need to be done to confirm this new finding, it's probably good timing that our new perspective on Alzheimer's disease includes several biomarkers (like spinal fluid abnormalities) that can be measured years before symptoms like memory loss and personality change take place.
