RESUMEN
This study was designed to evaluate the predictive value of event-related potential (ERP; N2 and P3b) in patients with mild cognitive impairment (MCI). Seventy-one patients with MCI were selected and compared with 31 healthy control subjects. They benefited from an initial assessment that included a neuropsychological evaluation and ERP. We followed them up for 1 year, and during their last visit, they benefited again from ERP and neuropsychological tests. At the end of the study, 2 subgroups of patients with MCI were differentiated according to their clinical evolution from baseline to follow-up: 41 MCI progressors (MCI-P) and 30 MCI nonprogressors (MCI-non P). The MCI-P patients had a significant decline in their executive functions compared with the MCI-non-P group at baseline and follow-up especially on trail making test B (TMT B) and verbal fluency (P < 0.0001). At baseline, MCI-P had increased P3b latencies and low P3b amplitudes compared with MCI-non P. The MCI-P showed an inversion of the P3b rostrocaudal gradient with a significant decrease in the amplitude of P3b in the parietal area compared with the MCI-non P. At follow-up, 17 MCI-P patients had converted to Alzheimer's disease (AD). There was a significant rate of decline of the amplitude of N2 and P3b in the frontal area among the groups. Furthermore, the MCI-P had a higher decrease in the rostrocaudal gradient of P3b and prolonged N2 and P3b latencies than the MCI-non P did. The sensitivity and specificity were approximately 80% and 70%, using P3b amplitude to discriminate the MCI-P from the MCI-non P. Our study underlines the interest of using N2 and P3b as neurophysiological markers for measuring MCI decline progression.