There has been much progress in the understanding of the biology of Alzheimer’s disease. Chemicals detected in the blood and spinal fluid of patients with Alzheimer’s and findings with new brain imaging techniques are the long sought after “biomarkers” of the disease. They are clues to its cause that are already targets for drug development. But there is a great public health danger in jumping the gun and prematurely using biomarkers in clinical practice for diagnosis or prognosis. It is for this reason that I have serious reservations about the new diagnostic guidelines proposed for the diagnosis of Alzheimer’s disease.
The current guidelines, which have served as well as possible for 26 years are based entirely on the patient’s narrative. The diagnostic label is applied when there is no better explanation for a severe and global compromise in cognition that developed insidiously. The diagnosis of Alzheimer’s when it is full blown is not a challenge. The challenge is in making the diagnosis when it is less obvious, when it is but “Possible” or “Probable.” These categories are confronted in the old criteria by considering the degree to which elements of cognition are compromised. The application of these qualified diagnostic labels provokes as much anxiety in the clinician as it does angst in the patient and foreboding in the patient’s intimate community. Maybe the fact that grandpa occasionally forgets his keys or his neighbor’s name is all there is to it; “grandpa’s losing it” or has a touch of “senility”. That would call for a supportive community, and not the specter of a slide to a dreadful fate denoted by Alzheimer’s.
