Cognitive potential P300 in Parkinson's disease

Cognitive evoked potential P300 in response to visual verbal and non-verbal stimuli was examined in 40 patients with idiopathic Parkinson's disease (PD) without cognitive impairment and 8 age- and sex matched normal controls. All the patients were subjected to clinical and neuropsychological evaluation. The influence of patient's age, duration, type and severity of the disease, debut's lateralization and anti-parkinsonic therapy efficacy on P300 was evaluated. Compared to controls, PD patients exhibited a significantly prolonged P300 latency and decreased P300 peak amplitude. The topography of PD maximum P300 amplitude indicated a frontal distribution with no between-hemispheres differences. Overall, the P300 changes in PD patients without dementia can be interpreted as a decrease of directed activity level and the partial defect of mental recognition processes and stimuli differentiation related mostly to the nonverbal image-spatial cognitive processes. The results show that P300 recording may be useful for diagnosis of subclinical cognitive disturbances in PD without dementia.