Plasma levels of antioxidant vitamins C and E are decreased in vascular parkinsonism

Abstract

Oxidative stress is an important mechanism of cell death in Parkinson's disease (PD) and brain ischemia. Vitamins C, E and A are important antioxidants and deficiency of these agents has been implicated in the mechanisms of atherosclerosis. We measured the levels of the above antioxidant vitamins in 44 patients with PD, 12 patients with vascular parkinsonism (VP), 11 patients with other parkinsonism syndromes of various causes and 39 controls. Vitamin A levels did not differ between groups. Vitamins C and E were found decreased in VP, while they were normal in PD indicating low levels of antioxidant vitamins in VP and stressing the necessity of maintaining sufficient dietary intake of these agents in the elderly.

Introduction

It has been widely accepted that oxidative stress is an important final mechanism of cell death in many neurodegenerative disorders including Parkinson's disease (PD) [1], [2]. Vitamin C (ascorbate) is an important water-soluble antioxidant that protects neurons from oxidative damage directly and indirectly, by restoring the reduced form of vitamin E [3], [4]. Vitamin E is a lipid-soluble, chain-breaking antioxidant that protects cellular and subcellular membranes from lipid peroxidation [5]; vitamin A is another important lipid soluble antioxidant [6]. Data on the blood levels and dietary intake of antioxidant vitamins in PD are conflicting. Several authors have reported decreased ascorbate levels [7], [8], while others have reported either normal [9] or increased levels [10] and normal dietary intake [11], [12]. Blood levels and/or dietary intake of vitamin E have been reported either decreased [8], [12] or normal [10], [11], [13]. An increased risk for PD was observed with lower dietary intake of vitamin E, but not vitamin C or carotene in one study [12] or with decreased previous intake of vitamin C and probably carotene but not vitamin E in another study [14]. Methodological differences and differences in dietary habits of the various ethnic groups studied may account for these discrepancies.

Oxidative stress and/or deficiency of antioxidant vitamins such as C and E have also been shown to participate in neuronal ischemia [1] and in the process of atherogenesis [15], [16]. Vascular parkinsonism (VP) is a recently reestablished heterogeneous entity [17] and its clinical, pathological and pathophysiological characteristics are currently under investigation [18], [19], [20]. It is caused by multiple lacunar or nonlacunar infarcts in the basal ganglia or white matter, etat grible, Binswanger's disease or, rarely, a single focal ischemic infarct or hemorrhage [21]. Clinical characteristics useful for the differentiation from PD include gait disorder, postural instability, absence of tremor, older age, unsatisfactory response to l-dopa and various combinations of cognitive decline, pyramidal and pseudobulbar signs [18].

The aim of the present cross-sectional study was to determine the plasma levels of vitamins C, E and A in PD and vascular parkinsonism in the Greek population.