DIAGNOSTIC-CRITERIA FOR NEUROPATHOLOGIC ASSESSMENT OF ALZHEIMERS-DISEASE

Prior to any evaluation cf morphologic brain change, a decision must b e made whether a given alteration is associated with aging or with dis ease. Patients with disease-related lesions may be in a clinically sil ent phase of a disease or show overt symptoms. Neurofibrillary tangles and neuropil threads are the hallmarks of Alzheimer's disease. They s hould nor be considered to be age-related changes, even when they are present only in small numbers. In general, the initial changes consist of neurofibrillary tangles and neuropil threads. Plaques (amyloid dep osits and/or neuritic plaques) are consistently present in the end sta ge of the disease. Initial neurofibrillary tangles and neuropil thread s develop at specific cortical predilection sites. The changes;hen spr ead in a predictable. nonrandom manner across other portions of the te lencephalic cortex. The sequential changes in the distribution pattern of the lesions provide the basis for a staging procedure that takes t he slow and gradual progression of the destructive process into consid eration. The staging procedure provides accurate diagnoses in the init ial stages and even reveals blain changes developing prior to the appe arance of clinical symptoms. It is thus advantageous in characterizing nondemented controls. The staging procedure can be carried out easily and does not require knowledge of clinical data, quantitative assessm ents, or adjustments for the age of the patients. Application of advan ced silver techniques (Gallyas, Campbell-Switzer) to demonstrate Alzhe imer's disease-related lesions also allows recognition of the hallmark s of other disorders, such as Lewy body disease (Parkinson's disease) and dementia with argyrophilic grains, which frequently co-occur with Alzheimer's disease.