Brain aging is a complex natural process characterized by the aging of brain proteins and acquisition of toxicity. It begins early in life and escalates with age. Brain protein aging includes a broad range of processes of protein modifications such as phosphorylation, protein structural changes, glycation, methylation, protein-protein and protein-RNA interaction, common and rare variant transition, and the gain of toxic function. Brain aging gradually leads to neurodegeneration and memory loss. Dementia refers to a group of conditions characterized by impairment of at least two brain functions, such as memory loss and judgment. Studies have shown that dementia is not a part of biological aging. This book contains some path-breaking research studies on brain aging. It aims to help develop a better understanding of the relationship between aging and dementia. Researchers and students actively engaged in this area of study will find this book extremely helpful.