Alzheimer's disease (AD) is the most common form of senile dementia worldwide. Anosognosia, a deficit in self-awareness, is recognized as one of the core symptoms of Alzheimer's disease dementia, in which self-awareness gradually deteriorates with disease progression. Chapter one of this book discusses anosognosia in Alzheimer's disease. Chapter two examines whether pathological narcissistic personality predicts increased risk of neuropsychiatric symptoms in AD. Chapter three discusses the impairment of instrumental activities of daily living in mild-to-moderate AD patients. Chapter four studies the single nucleotide polymorphisms (SNPs) in four candidate genes, and compares their frequencies in healthy individuals with the frequencies in Venezuelans diagnosed with AD. Chapter five studies the role of IL-6 genotypes in the late-onset of AD. The last chapter evaluates the risk factors and protective factors for impairment in elderly individuals living in communities in Shanghai.