From Small to Big Molecules: How Do We Prevent and Delay the Progression of Age-Related Neurodegeneration?

Age-related neurodegeneration in the brain and retina is complicated. It comprises a series of events encompassing different modes of degeneration in neurons, as well as inflammation mediated by glial cells. Systemic inflammation and risk factors can contribute to disease progression. Age-related conditions such as Alzheimer's disease (AD), Parkinson's disease (PD) and Age-related Macular Degeneration (AMD) affect patients for 5 to 20 years and are highly associated with risk factors such as hyperhomocysteinaemia, hypercholesterolaemia, hypertension, and symptoms of mood disorder. The long duration of the degeneration and the wide array of systemic factors provide the opportunity for nutraceutical intervention to prevent or delay disease progression. Small molecules such as phenolic compounds are candidates for neuroprotection because they have anti-oxidant activities and can modulate intracellular signaling pathways. Bigger entities such as oligosaccharides and polysaccharides have often been neglected because of their complex structure. However, certain big molecules can provide neuroprotective effects. They may also have a wide spectrum of action against risk factors. In this review we use an integrative approach to the potential uses of nutraceutical products to prevent age-related neurodegeneration. These include direct effects of phenolic compounds and polysaccharides on neurons to antagonize various neurodegenerative mechanisms in AD, PD and AMD, and indirect effects of these compounds on peripheral disease-related risk factors.