THE P1 COMPONENT OF THE MIDDLE LATENCY AUDITORY-EVOKED POTENTIAL PREDICTS A PRACTICE EFFECT DURING CLINICAL-TRIALS IN ALZHEIMERS-DISEASE

Article abstract-Thirty-five patients with probable Alzheimer's diseas e who were enrolled in an experimental drug trial of linopirdine under went repeated testing that included recording the middle latency audit ory evoked potential (MLAEP), the Mini-Mental State Examination (MMSE) , and the Alzheimer's Disease Assessment Scale Cognitive Subscale (ADA SCOG). Patients lacking the P1 component of the MLAEP exhibited a sign ificantly greater decline in cognitive function as measured by the ADA SCOG over 56 weeks. This decline appeared to be due to a less robust p ractice effect, which was maximal in all patients at 16 weeks. At the end of 56 weeks the entire group of patients was near baseline with re spect to the ADASCOG. This lack of the annualized decline expected fro m other longitudinal studies may be explained by practice and placebo effects. The MMSE did not exhibit a practice effect and showed the exp ected decline in scores.