Possible neurophysiological markers of genetic predisposition to Alzheimer's disease.

Visual-evoked potentials (VEP) to a flash were studied in the first-order relatives of patients with Alzheimer's disease (AD) (mean age 38.2 +/- 2.6 years) in comparison with the patients (mean age 61.9 +/- 1.4 years) and age-matched normal controls. It was found that in the relatives of AD patients the latencies of N2, P3, N3 components were delayed compared with the age-matched normal controls. The delay in the latencies of the patients and their relatives concerned the same components but was smaller in the relatives of AD patients. The amplitude of the P2, N2 components was increased in the latter. The neurophysiological alteration in AD patients' relatives may be considered as signs of a latent neurodegeneration in limbico-reticulo-cortical pathways, which may be connected to the pathological hyperactivity of limbico-reticulo-cortical structures.