WASHINGTON -- Clinical diagnosis of Alzheimer's disease may be just as accurate as neuroimaging, blood work, and interview of a knowledgeable informant, David A. Bennett, M.D., said at an international conference sponsored by the Alzheimer's Association.
Rates of pathologic confirmation of clinical AD, made without the benefit of such diagnostic tools, in the Religious Orders Study (ROS) and the Rush Memory and Aging Project (MAP) compared favorably with confirmation rates in a clinic-based setting that took advantage of as many diagnostic aids as necessary, said Dr. Bennett, director of the Alzheimer's Disease Center at Rush University Medical Center in Chicago.
The ROS is following more than 1,000 older religious clergy from across the United States, who have agreed to medical and psychological evaluation each year and brain donation after death for autopsy. The Rush MAP is following more than 1,000 residents of 40 retirement homes and senior housing facilities in the Chicago area, who also have agreed to medical and psychologic evaluation each year and donation of the brain, spinal cord, and selected nerves and muscles after death.
The two studies have been major undertakings, involving thousands of clinical evaluations. To reduce costs and provide uniformity of the evaluations, the researchers in both studies avoid using informants, neuroimaging, blood work or routine consensus conferencing. Instead, they rely on a system of guided clinical judgment developed for the studies. The system combines actuarial prediction rules with clinical judgment.
Each year the researchers evaluate each participant using complete neuropsychologic evaluations, involving about 20 tests--11 of which have age-adjusted cutoff scores.
A neuropsychologist reviews selected data from the test results to determine the subject's level of cognition. A clinician also reviews selected data, interviews and examines the patient, and makes a determination about cognitive decline, stroke, Parkinson's disease, depression, and other common conditions.
Selected data from these evaluations then are entered into a software actuarial decision tree to make a clinical diagnosis. The clinician has the opportunity to override the computer-generated decision. Clinicians and specialists are blinded to the previous years' results. When a participant dies, all the clinical data are reviewed by a neurologist, who makes a final clinical diagnosis.
Rates of the pathological confirmation of disease from the ROS and Rush MAP studies were compared with those from the Rush Alzheimer's Disease Center clinic, where over 600 Chicago-area patients, who have agreed to annual evaluations and brain donation upon death are treated.
"In the clinic, we follow the commonly accepted procedures, consistent with the current practice parameters--detailed neuropsychological testing, an interview with a knowledgeable informant, structural neuroimaging, blood work, and other ancillary tests that are clinically indicated," said Dr. …