Plasma chain-breaking antioxidants in Alzheimer's disease, vascular dementia and Parkinson's disease

We studied the plasma chain-breaking antioxidants a carotene, beta carotene , lycopene, Vitamin A, Vitamin C, Vitamin E and a measure of total antioxid ant capacity, TAG, in 79 patients with Alzheimer's disease (AD), 37 patient s with vascular dementia (VaD), 18 patients with Parkinson's disease and de mentia (PDem), and 58 matching controls, together with 41 patients with Par kinson's disease (PD) and 41 matching controls. Significant reductions in i ndividual antioxidants were observed in all dementia groups. When compared to controls, the following were reduced: Vitamin A in AD (p<0.01) and VaD ( p<0.001); Vitamin C in AD (p<0.001), VaD (p<0.001) and PDem (p<0.01); Vitam in E in AD (p<0.01) and VaD (p<0.001); beta carotene in VaD (p=0.01); lycop ene in PDem (p<0.001). Lycopene was also reduced in PDem compared to AD (p < 0.001) and VaD (p < 0.001). Antioxidant levels in PD were not depleted. N o significant change in TAC was seen in any group. The reduction in plasma chain-breaking antioxidants in patients with dementia may reflect an increa sed free-radical activity, and a common role in cognitive impairment in the se conditions. Increased free-radical activity in VaD and PDem could be ass ociated with concomitant AD pathology. Individual antioxidant changes are n ot reflected in TAG.