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 Hcy, 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 μmol/L, and 38.9% of the patients had Hcy level above the reference range (>15.0 μmol/L). The Hcy 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 Hcy 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-treatedPD 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.