Contribution of auditory P300 test in the diagnosis of mild cognitive impairment in parkinson's disease

In Parkinson's disease (PD) there is a spectrum of cognitive dysfunction, ranging from mild cognitive impairment (MCI) to PD dementia (PDD). Movement Disorder Society (MDS) proposed diagnostic criteria for mild cognitive impairment in Parkinson's Disease (PD-MCI) in 2012. Event-related potentials provide measuring cognitive functions. Abnormalities in P300 event-related potentials have been observed in PDD patients. However, in non demented ones, the P300 showed controversial results. There has not been any study about P300 changes in PD-MCI patients diagnosed according to MDS PD-MCI criteria. We aimed to investigate whether additional electrophysiological tests to help clinical diagnosis of mild cognitive impairment in Parkinson's disease and we evaluated P300 changes in patients with non demented Parkinson's disease and analyze correlation between cognitive features and P300 changes. 20 patients with Parkinson's disease who are diagnosed mild cognitive impairment (PD-MCI group) according to MDS 2012 PD-MCI level II criteria, 21 patients with Parkinson's disease without cognitive impairment (PD-Normal group) and 20 neurologically normal age, sex and education matched controls (Control group) were examined by standard auditory odd ball paradigm. N100, P200, N200, P300 latencies and peak-to-peak N100-P200, P200-N200, N200-P300 amplitudes were measured and analyzed. P300 latencies recorded from Fz, Cz and Pz and N200 latency recorded from Fz were significantly longer in PD-MCI group than in PD-Normal and Control group (respectively, p<0.001, p=0.041). P300 amplitude recorded from Fz was significantly lower in PD-MCI group than the other groups (p=0.038). While P300 was obtained all patients in PD-Normal and control group, it was loss 35% of PD-MCI patients. The results show that P300 provide us a diagnostic tool for detecting mild cognitive impairment in Parkinson's disease. We suggest that P300 prolongation and loss of P300 latency could be included PD - MCI diagnostic criteria as a supportive criteria