Clinical significance of homocysteine (hcy) on dementia in Parkinson's disease (PD)

Cognitive dysfunction and dementia are common non-motor symptoms of PD. hcy has various neuronal and endothelial cellular toxicities. The clinical relevance of the levodopa associated with elevated hcy level and its effect on the course of cognitive decline in PD are still undetermined. We conducted this study to clarify the clinical significance of elevated hcy in PD associated with dementia in the Korean population. A total of 33 PD patients without dementia (PDwoD) and 28 PD patients with dementia (PDD) who were recruited for this study were compared with 48 HCs to confirm the value of hcy as a contributing factor of dementia associated with PD. PD patients had neuropsychological tests and neurological examinations performed. The plasma hcy level was measured routinely in all patients and HCs. The hcy of PDD showed a higher hcy level than those of PDwoD as well as HCs. In considering each group of PDwoD and PDD, there were no intercorrelations between hcy levels, duration of PD symptoms, duration of PD treatment, or the results of neuropsychological tests. In conclusion, we ascertained that hcy level was related to the cognitive decline of PD patients. However we were unable to confirm a clear pathophysiologic role of hcy in PDD and the relationship between hcy and levodopa, significantly.