NFTs and neuritic plaques are considered the signature lesions of AD without them AD does not occur. Plaques and tangles may also be present in other disease, even in normal aging, but there is a much higher concentration of plaques and tangles in patients with AD (13) .
OXIDATIVE STRESS AND ALZHEIMER’S DISEASE
Oxidative stress play important role in age-associated cognitive impairment, and also in Alzheimer’s disease. Brains from AD patients exhibit significantly increased levels of protein oxidation.(14),(15) lipid peroxidation and electron transport chain deficiencies, thus supporting a role for mitochondria in AD-related oxidative stress. Oxidative stress could be responsible for the cognitive deficits observed in Alzheimer’s disease because it might damage key molecular and cellular components underlying cognitive function.(16). In addition, oxidative stress could also be a mediator in neuron cell death in Alzheimer’s disease, since reactive oxygen species (ROS) production accompanies Aβ-induced neuronal apoptosis and the inhibition of Aβ-induced neuronal apoptosis by the antioxidants α-tocopherol and N-acetylcysteine.(17) Harris ME et al 1995).Aβ has been shown to induce ROS production in both neuronal(18and astrocyte cell cultures. In addition, cultured hippocampal neurons and synaptosomes exhibit increased protein oxidation when incubated with various Aβ peptides(19) (AvdulovNA et al 1997). Furthermore, treating rat synaptic plasma membranes with either Aβ(1-40) or Aβ(25-35) also increased lipid peroxidation(20) However, Aβ might not be the only cause for oxidative stress in Alzheimer’s disease. Brains from AD patients exhibit damaged mitochondria and reduced ATP production(21)
AGE-RELATED COGNITIVE IMPAIRMENT ASSOCIATED WITH OXIDATIVE STRESS
In addition to the strong correlation between aging and oxidative stress, a number of studies have demonstrated a link between age-related oxidative stress and cognitive impairment. The decline in learning and memory exhibited by aged mice tested in the spatial swim maze has been correlated to increased protein carbonyl content in cerebral cortex, and the poor motor coordination these aged mice also displayed was correlated to increased protein oxidation in cerebellum. In humans, lipid per oxidation is also significantly higher in hippocampus and inferior parietal lobule of elderly individuals who exhibit mild cognitive impairment (22) (Nicolle...