Relationship between plasma homocysteine levels and cognitive functions in Parkinson’s patients

Objective: In this study we aimed to research the relationship between homocysteine levels and cognitive functions in IPD and to find out whether cognitive functions in IPD were associated to age, disease duration, age of disease onset, stage, the Unified Parkinson Disease Rating Scale (UPDRS) vitamin B12, folic acid and to assess the impact of entacapone on plasma levels of hcy, vitamin B12 and folat levels and MMSE scores in IPD.

Methods: Forty-two patients with IPD (26 male, 16 female) who attended our movement disorders outpatient clinic were included in this study. The diagnosis of IPD was confirmed by a movement disorders specialists in Neurology, according to UK Parkinson’s Disease Society Brain Bank Criteria. First of all the hcy, folic acid and vitamin B12 levels and the results of screened cognitive evolution by mean MMSE of IPD patients were compared with those of the controls. Then patients were divided in two groups: 1) patients treated with only L-Dopa 2) patients treated with L-Dopa and entacapone combination. The hcy, folic acid and vitamin B12 levels of the patients with levodopa and levodopa+entacapone groups and the control group were compared.

Results: Sixteen patients with IPD receiving levodopa+entacapone treatment, 28 patients with IPD receiving only levodopa treatment and 26 healthy subjects were included in this study. MMSE scores were higher in the only L-dopa treated group than in the entocapone+Ldopa treated group and also the control group (27.23±3.03, 25.81±1.97, 26.23±1.96 p=0.004 p=0.006, resp.). There was no significant difference between the entacapone+levadopa treated group and the control group in post-hoc analysis (p=0.29). Homocysteine levels were found higher in the only L-dopa treated group than the other groups. (14.67±4.83, 12.74±3.28, 12.81±3.26 p=0.34, resp.).

Conclusion: Our study shows that patients treated with L-DOPA have increased HCY concentrations, which is thought to be dosedependent, and combination with entacopone may decrease homocysteine levels in PD patients. However, we found no correlation between cognitive impairment, hcy levels and stage of disease, age of onset of the disease, or duration of the disease.