Clinical Diagnosis of Alzheimer's Disease

Abstract

There are a number of ways in which a clinical diagnosis of dementia of the Alzheimer type can be made – the application of clinical criteria is the commonest but ancillary techniques such as neuroimaging, peripheral markers and neurophysiological investigations are helpful. The NINCDS/ADRDA criteria are the most consistent in correctly predicting, during life, who will have the neuropathological findings of Alzheimer''s disease and as such represent the gold standard for clinical diagnosis. Platelet membrane fluidity and the results of nasal biopsy may also be helpful but the specificity of abnormalities for Alzheimer''s disease has yet to be established. Computerised tomography and single photon emission tomography are the two most applicable and widely available neuroimaging techniques and, with single photon emission tomography, characteristic patterns of blood flow distribution are seen in Alzheimer''s disease. Even with the application of clinical guidelines and appropriate use of ancillary investigations, there is still diagnostic misclassification in up to 20% of cases for the refinement of clinical criteria and prospective clinico-pathological studies along with clinical criteria for other types of dementia are required.

Down's syndrome, dementia and macrocytosis

“…The identification of specific genetic or biological markers associated with Alzheimer's disease (AD) would be a tremendous advance in the research and clinical management of this form of dementia. It would improve the clinical diagnostic accuracy (use of clinical diagnosis alone can lead to a misdiagnosis in 20%-30% of cases in the non-LD (learning disability) population, 1 aid early detection, improve quality of treatment trials, increase our knowledge of the pathogenesis of the disorder and determine if AD is a specific brain disease or a generalised system disorder. Further, as a diagnosis of AD is often made by exclusion of other disorders; such a biological measure would be a 'positive' indicator of AD.…”