Neurochemical Aspects of Alzheimer's Disease - Chapter 2: Risk Factors for Alzheimer’s Disease

Alzheimer’s disease (AD) is the most common age-related neurodegenerative disorder associated with dementia and the progressive deterioration of memory impairment, cognitive deficit, and personality changes. These symptoms are caused by substantial synaptic and neuronal loss in specific brain areas (neocortex, hippocampus, and other subcortical regions). The neuropathological features of AD include accumulation of amyloid β (Aβ) peptides and extracellular deposition of Aβ peptides in the form of senile plaques and in the cerebral blood vessels. Another hallmark of AD is the intracellular inclusion of neurofibrillary tangles, which are composed of hyperphosphorylated Tau protein. Risk factors for AD include normal aging, diet, sedentary lifestyle, sleep disturbances, genes [amyloid precursor protein (APP), presenilin 1 (PSEN1), PSEN2, and APOE], environmental factors, and epigenetic factors. AD is a multifactorial disease. So one risk factor alone cannot account for the pathogenesis of AD. However, several risk factors in combination may account for the pathogenic mechanism of AD.