Relationships between neurophysiological and immune parameters were studied in normal middle-aged and elderly subjects and in patients with dementia of Alzheimer's type (DAT). The rate of such interaction was minimal in normal aging, in DAT neuroimmune relations increased. The correlation between the immune parameters and the characteristics of components of visual evoked potentials and auditory brain-stem responses suggests that in the middle-aged healthy subjects, a primary role in neuroimmune relations belongs to limbicoreticular structures and to the mesencephalon. In normal aging, the influence of limbicoreticular structures on immune structures decreases. In DAT, the modulation of immune processes by limbicoreticular and thalamocortical structures, as well as the pontobulbar part of the brain stem increases. In middle age and in DAT, persons with different functional brain asymmetry (as estimated from electrophysiological criteria) have different lymphocytic functional activities and rates of neuroimmune interactions.