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January 1993

Reliability and Usefulness of a New Immunochemical Assay for Alzheimer's Disease

Author Affiliations

From the Departments of Neurology (Drs Chui and Perlmutter and Ms Zarow) and Preventive Medicine (Mr Quia), University of Southern California School of Medicine, Los Angeles; Rancho Los Amigos Medical Center, Downey, Calif (Dr Chui and Ms Zarow); and Abbott Laboratories, Abbott Park, Ill (Drs Ghanbari and Miller). Drs Ghanbari and Miller are now with Molecular Geriatrics, Inc, Libertyville, Ill, Rancho Los Amigos Medical Center, 12838 Erickson St, Downey, CA 90242 (Dr Chui).

Arch Neurol. 1993;50(1):57-63. doi:10.1001/archneur.1993.00540010051017

• Objective.  —To assess the reliability and usefulness of a new sandwich enzyme-linked immunoassay (ALZ-EIA) that detects Alzheimer's disease-associated proteins in the diagnosis of Alzheimer's disease.

Design.  —The reliability of the assay was assessed between two laboratories. Sensitivity and specificity of a diagnostic algorithm based on the results of the ALZ-EIA were determined using the Consortium to Establish a Registry for Alzheimer's Disease neuropathological diagnoses as the "gold standard."

Setting.  —Autopsy cases were obtained from a teaching hospital with a specialized Alzheimer Disease Diagnostic and Treatment Center.

Cases.  —Brain tissue was selected from 24 cases with dementia and 10 normal controls.

Main Outcome Measures.  —Optical density measurements from the ALZ-EIA in the hippocampus and three neocortical regions.

Results.  —A 95% concordance in ALZ-EIA activity was found between the two laboratories, and an 85% concordance was found between ALZ-EIA and the Consortium to Establish a Registry for Alzheimer's Disease diagnoses. Perfect agreement was obtained for "typical" Alzheimer's disease cases (those with plaques and tangles), while discrepancies occurred for "atypical" cases (those with predominantly plaques or tangles).

Conclusions.  —The ALZ-EIA provides a highly reliable method of assessing neurofibrillary degeneration. Its clinical usefulness as a diagnostic test would be enhanced by the availability of a complementary assay for β-amyloid.