With ageing of populations, the worldwide population of persons with dementia will reach over 81 million by 2040, of which the most common cause is Alzheimer's disease. In recent years, there have been major advances in the understanding of its pathogenesis, methods to diagnose it, and treatment. Magnetic resonance brain imaging, cerebrospinal fluid biomarkers, and Pittsburgh compound B and fluorodeoxyglucose positron emission tomography of the brain can facilitate an accurate diagnosis of Alzheimer's disease in its early stage, and diagnose the mild cognitive impairment stage of Alzheimer's disease. At present, only symptomatic but not disease-modifying drug treatments are available. Donepezil, rivastigmine and galantamine are the currently approved cholinesterase inhibitors for the treatment of mild, moderate, and severe Alzheimer's disease. Overall, cholinesterase inhibitors show beneficial effects on cognition, activity of daily living, behaviour, and overall clinical rating. Memantine is another symptomatic treatment for moderate-to-severe Alzheimer's disease patients. It has a small beneficial effect on cognition, activity of daily living, behaviour, and overall clinical rating. Vitamin E has antioxidant properties, and may be used in some Alzheimer's disease patients without vascular risk factors. Concurrent non-pharmacological and psychosocial management of patients and their caregivers have a very important role. Disease-modifying therapies are still under development, whilst immunotherapy may be a viable option in the near future.