P300 Cognitive Evoked-potential and Pattern of Learning Impairments in Idiopathic Parkinson's Disease

ABSTRACT

To evaluate P300 cognitive evoked-potential, the pattern of learning impairment and their possible relationship in patients with idiopathic Parkinson's disease, we performed P300 cognitive potential test and neuropsychologic tests evaluating learning ability-Gollin's incomplete drawing test (GIDT) , the tower of Hanoi Puzzle (TOHP), and recall the name of pictures in Gollin's incomplete drawing test (GIDT recall), on 37 patients with idiopathic Parkinson's disease (19 never-medicated and 18 with levodopa therapy for more than 6 months) and age- and sex-matched normal healthy controls. Compared with controls, patients showed significant delay in P300 latency and significant impairment in TOHP and GIDT recall, but not in GIDT. The revodopa-treated patients showed significantly shorter P300 latency and better performance in TOHP than never-medicated patients, although they still showed impairments in both tests compared with controls. Although all neuropsychologic tests used in present study significantly correlated to the P300 latency in patients, the most significant correlation was found in TOHP. These results suggest, first, the P300 latency significantly delayed in parkinsonian patients which is partially improved by levodopa therapy ; second, visuomotor procedural learning but not visuoperceptual procedural learning is impaired in parkinsonian patients which is also partially responsive to levodopa therapy third, although visuoperceptual procedural learning is not impaired, the transformation process of procedural learning into declarative learning is probably impaired in Parkinson's disease ; fourth, the dopaminergic lesion in Parkinson's desease may have a role in producing both P300 abnormality and impairments in visuomotor procedural learning.