Antioxidants in the prevention and treatment of alzheimer’s disease

Alzheimer’s disease (AD) is the most common human neurodegenerative disease that causes dementia in the elderly. A person suffering with AD shows gradual memory deterioration and other cognitive discrepancies, which eventually lead to complete incapacity and ultimately death. The major pathological characteristics of AD are the presence of senile plaques extracellularly and neurofibrillary tangles intracellularly. Growing evidences have demonstrated that oxidative stress is an important factor contributing to the initiation and progression of AD. However, the exact mechanisms that lead to the disruption of redox balance and the sources of free radicals remain elusive. The excessive reactive oxygen species may be generated from mechanisms such as mitochondrial dysfunction and/or aberrant accumulation of transition metals, while the abnormal accumulation of amyloid-β protein (Aβ) and tau proteins appears to promote redox imbalance. The resulting oxidative stress has been implicated in Aβ or tau-induced neurotoxicity. To combat oxidative stress in AD, antioxidants have been therapeutically implicated. Within the last few years, a number of polyphenolic compounds with antioxidant and neuroprotective effects have been described to possibly benefit AD patients. Many efforts have been made to explore the mechanisms behind the neuroprotective action of polyphenols. The aim of this chapter is to critically review the use of different types of antioxidants in the prevention and treatment of AD.