Alzheimer's disease (AD) is a complicated neurological condition that has a high global prevalence, particularly among the elderly. The epidemiology, pathogenesis, risk factors, diagnosis, treatment modalities, preventive measures, and the most recent developments in gene therapy, immunotherapy, and nanomedicine are all included in this review of AD. AD is pathophysiologically characterised by several hypotheses, including the amyloid cascade theory, cholinergic theory, hyperphosphorylated Tau protein hypothesis, oxidative stress hypothesis, and metal ion theory. The development of AD is influenced by a number of factors, including genetics, environmental exposures, lifestyle decisions, vascular problems, metabolic disorders, neurological and behavioural illnesses, and inflammatory processes. Effective management requires accurate diagnosis and assessment, which includes a variety of psychiatric, neurological, physical, and cognitive examinations as well as biomarker analysis employing body fluid markers and neuroimaging techniques. N-methyl D-aspartate antagonists and cholinesterase inhibitors are the main treatments for AD, yet new developments in gene therapy, immunotherapy, and nanomedicine all present exciting possibilities for altering the course of the illness. Preventive tactics concentrate on risk variables that can be changed, like physical activity, drinking alcohol, quitting smoking, mental stimulation, controlling diabetes, controlling obesity, controlling blood pressure, participating in social activities, and receiving mental health care.