Plasma homocysteine levels and Parkinson disease: Disease progression, carotid intima-media thickness and neuropsychiatric complications

Objective: To determine whether plasma homocysteine (Hcy) levels are associated with clinical characteristics, neuropsychological and psychiatric manifestations and cardiovascular comorbidity in patients with Parkinson disease (PD). Background: Elevated Hcy levels are linked to atherosclerosis, vascular disease, depression, and dementia. Patients with PD treated with L-dopa have been shown to have elevated Hcy levels. Design/Methods: Idiopathic PD patients were evaluated using the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr stage, Parkinson Psychosis Rating Scale, Beck Depression Inventory, Frontal Assessment Battery, Mini-Mental Status Examination, and several tests for frontal type cognitive functions. Fasting blood samples were collected for the measurement of Hey, and carotid B-mode ultrasound was performed to measure intima-media thickness of the common carotid arteries. Results: Seventy-two consecutive PD patients (46 men; average age, 68.7 +/- 11.6 years; average disease duration, 7.0 +/- 4.7 years) were recruited. All but 10 patients were treated with L-dopa. The average level of Hcy was 16.4 +/- 7.8 mu mol/L, and 38.9% of the patients had Hcy level above the reference range (> 15.0 mu mol/L). The Hey levels were associated with PD duration as they were with L-dopa treatment duration but were not associated with the parameters of disease severity or with L-dopa dose. The Hey levels were associated neither with the common carotid intima-media thickness nor with cardiovascular morbidity. No association was found between Hcy and the neuropsychiatric features of PD such as depression, cognitive performance, or psychosis. Conclusions: Hyperhomocystinemia is common in L-dopa-treated PD patients but was not associated with neuropsychological complications (depression, dementia, and cognitive decline associated with frontal lobe functioning or psychosis), enhanced disease severity, or vascular comorbidity.