Progression of Mild Cognitive Impairment to Alzheimer’s Disease: Improved Diagnostic Value of the Combined Use of N200 Latency and β-Amyloid(1–42) Levels

<i>Background/Aims:</i> The aim of this study was to investigate the role of cerebrospinal fluid β-amyloid(1–42) levels and auditory event-related potentials (AERPs) in the progress of mild cognitive impairment (MCI) to Alzheimer’s disease (AD). <i>Methods:</i> In 53 MCI patients, lumbar puncture was performed and β-amyloid(1–42) levels were determined. Twenty patients were reexamined after 11 months. During this period, 5 of them progressed to AD. Neuropsychological and ERP analyses were performed on all patients during both baseline and endpoint examinations. <i>Results:</i> Compared to stable MCI patients, those that progressed to AD had significantly lower β-amyloid(1–42) levels (Mann-Whitney test, Z = –2.952, p = 0.003; effect size r = –0.41) and significantly prolonged N200 latencies (Mann-Whitney test, Z = –3.561, p < 0.001, effect size r = –0.49). From ERP variables, only the N200 latency significantly correlated with β-amyloid(1–42) levels (baseline examination: r_s = –0.421, p = 0.002; follow-up examination: r_s = –0.574, p = 0.008). <i>Conclusions:</i> The combined use of these two parameters enabled discrimination of stable MCI patients from those who developed AD, with 100% sensitivity and specificity. Therefore, this method could be of high diagnostic value for the early diagnosis of AD.