Event-related brain potentials to Memory Workload and 'Analytical-SpecificPerception' (Mangina-Test) in patients with early Alzheimer's Disease and in normal controls

Our previous research with intra-cerebral event-related potentials in conju nction with an original Memory Workload Paradigm has shown that significant load effects for the N4 latency were found only for both amygdalae and the left posterior hippocampus as well as for both anterior neo-cortical regio ns of the temporal gyri. These same structures are also affected in Alzheim er's Disease. Therefore, based on our previous intra-cerebral findings, our present research was to use our novel Memory Workload Paradigm in conjunct ion with surface ERPs as neurophysiological markers to tap cerebral regions and functions involved in memory disorders pertaining to early Alzheimer's Disease as opposed to normal memory processes in age-matched normal contro l subjects. Moreover, the Mangina-Test which measures varying degrees of 'A nalytical-Specific Visual Perception' was individually administered to all patients and controls in separate sessions. Results indicate that for the e arly Alzheimer's Disease group, a significant main effect for memory load w as found for the P400 amplitude (F-3,F-30 = 4.52, P < 0.02) which was absen t in the normal group. In particular, the P400 amplitude was significantly higher on posterior head regions for patients with early Alzheimer's Diseas e as opposed to age-matched normal subjects (F-7,F-140 = 3.54, P < 0.03) wh ich distinguished both groups (F-1,F-20 = 6.13, P < 0.03). For the P400 lat ency, a significant memory load effect was present only for the normal grou p (F-3,F-30 = 11.26, P < 0.01). The Mangina-Test performance clearly differ entiated both groups (F-1,F-19 = 105.85, P < 0.001). The present data provi de the first valuable evidence that ERPs to our novel Memory Workload Parad igm are sensitive neurophysiological diagnostic markers which delineate the early clinical brain irregularities underlying early Alzheimer's Disease a s opposed to the normal memory processes of age-matched normal subjects. In addition, their use could be valuable for the objective clinical follow-up of therapeutic interventions in early Alzheimer's Disease. (C) 2000 Elsevi er Science B.V. All rights reserved.