Alzheimer's disease and normal aging: Neurophysiological and immunological aspects

We studied in humans the characteristics of brain visual evoked potentials (EP) elicited by presentation of a reverse chess-board pattern and also the following parameters of the immune status: the numbers of T- and B-lymphocytes, immunoglobulin levels in blood plasma. and level of sensibilization of lymphocytes to the brain antigen. Two groups were examined: aged persons (up to 65 years) with normal course of aging (the control group) and patients of the same age suffering from Alzheimer's disease (AD). In the latter group, lower amplitudes of early and late EP components (P300, in particular) and longer peak latencies of late components were observed. The development of AD correlates with a drop in the number of lymphocytes, increased IgA level, and sensibilization of lymphocytes to brain antigen, which is indicative of an immunodeficit state and the development of an autoimmune process; the latter phenomena can be significant factors responsible for neuronal death.