Abstract

Objective: Idiopathic Parkinson’s disease is a clinical situation characterized by akinesia, rigidity, and tremor, and results from the degeneration of the dopaminergic nervous system. As the disease progresses over time, depression, cognitive dysfunction and alterations in cognitive functions are added to the movement disorder at varying rates. The P300 component is a useful parameter for cognitive processing studies on PD patients, as it is independent from motor skills. The current study aimed to show the effects of the PD on the cognitive functions by evaluating the cognitive functions of IPD patients without dementia with the help of an event related potential component, P300 test.

Methods: Thirty-eight patients (25 males and 13 females), ranging in age between 40 and 80 years (mean: 58.8 years), were included to the study and the control group consisted of 39 volunteers (25 males and 14 females), ranging in age between 44 and 84 years (mean: 63.5 years), who did not have a history of cerebrovascular disease, dementia, or depression. The participants were informed about the content and the practice of the study, and informed consent forms were obtained. Neurological examination, standardized mini mental test, Unified Parkinson’s Disease Rating Scale (UPDRS), Hoehn and Yahr Scale, Hamilton Depression Rating Scale (HAM-D), and P300 tests were performed on the patients. Standardized mini mental test (SMMT), HAM-D, and P300 tests were performed in the control group.

Results: P300 latencies in Parkinson’s patients were significantly prolonged compared to the control group. There was a decrease in P300 amplitude values with increasing HAM-D.

Conclusion: P300 latency reflects the rate of stimuli classification by mental process, attention, and cognitive processing. Even if no dementia is present in PD patients, there is a dysfunction in these functions, and it can be demonstrated by the P300 test, which is independent from motor skills.

Key words: Cognitive functions, idiopathic Parkinson’s disease, P300-event related potentials