Alzheimer’s disease (AD) is the most common form of dementia that is considered as a multifactorial neurodegenerative disease which causes a gradual cognitive decline along with a significant socio-economic burden. In this chapter, a unitive approach is adopted to give an overview of AD pathophysiology, beginning with historical foundations and its classification into early-onset and late-onset variants, alongside familial and sporadic forms. It also critically examines both accepted and novel theories explaining AD pathogenesis-including the cholinergic deficit, amyloid-β cascade, tau hyperphosphorylation, neuroinflammation, oxidative stress, mitochondrial dysfunction, cholesterol dysregulation, vascular compromise, and aberrant cell cycle hypotheses. This chapter further evaluates the restrictions of the traditional treatment and explains the shift towards the disease-modifying therapeutic strategies, including monoclonal antibodies targeting amyloid (e.g., aducanumab, lecanemab, donanemab), tau inhibitors, and combination therapies. Also, the therapeutic strategies like phytotherapy, anti-oxidants, gut-microbiome, etc. are found to be as emerging approaches in the modern world.