Impaired novelty P3 potentials in multiple system atrophy - correlation with orthostatic hypotension

Although neuropsychological tests demonstrate frontal lobe dysfunction in m ultiple system atrophy (MSA), assessment of frontal function using event-re lated brain potentials (ERPs) has not been sufficiently performed in MSA. T he correlation between frontal lobe dysfunction and orthostatic hypotension (OH), which is known to cause frontal hypoperfusion, remains unclear. Our objectives were to assess frontal lobe dysfunction in MSA patients using ER Ps and to elucidate the relevance of OH to changes in ERPs. Nine consecutiv e patients with MSA and nine age- and gender-matched healthy controls were compared by performance in the Wisconsin Card Sorting Test (WCST) and somat osensory ERPs to target and novel stimuli, namely, parietal maximal P3 (tar get P3) and fronto-central P3 (novelty P3), respectively. The correlation b etween novelty P3 and OH was evaluated in the MSA group. The MSA group show ed a poorer performance in categories achieved (CA), total errors (TE) and perseverative errors by Nelson's (PEN) method in the WCST compared with the control group (CA and PEN: p < 0.01; TE: p < 0.02). Novelty and target P3s in the MSA group showed significantly prolonged latency (novelty: p < 0.05 ; target: p < 0.01) and reduced amplitude (novelty: p < 0.02; target: p < 0 .01) compared with the control group. There was a significant negative corr elation between novelty P3 latency and a drop in systolic blood pressure (r = 0.76; p < 0.02). Abnormalities of novelty P3 in the MSA group might refl ect frontal lobe dysfunction, namely failure of attentional set-shifting, t hat was identified by the WCST. OH may play a role in the development of fr ontal lobe dysfunction in MSA. (C) 2001 Elsevier Science B.V. All rights re served.