ABSTRACT
Free radicals are chemical species that have a single unpaired electron in an outer orbit. Energy created by this unstable configuration is released through reactions with adjacent molecules, causing damage to these molecules. The free radical, superoxide O2·¯, may be formed during the normal cellular handling of oxygen, and is itself toxic. It is converted to hydrogen peroxide by superoxide dismutase. Brugge and colleagues found increased activity of superoxide dismutase in the erythrocytes of individuals with Down syndrome (DS), and a variable 'compensatory' elevation in glutathione peroxidase activity in these cells. One such overexpressed gene is superoxide dismutase which, through a process of altered free radical stress, may cause, or at least be involved in, the processes of accelerated ageing, cataract formation and early dementia. Dementia and epilepsy tend to occur simultaneously in DS, and could be related to excess hydroxyl radical activity.
