Alzheimer's disease (AD) is the commonest form of dementia in developed countries, accounting for approx. 50-60% of the overall cases of dementia among persons over 65 years of age. Furthermore, because of the world's ageing population, and without an effective prevention or treatment, a sharp rise in the prevalence of dementia with age is predicted. AD itself is a progressive and irreversible neurodegenerative disorder associated with three main clinical features in the domains of declines in cognitive function (neuropsychologic) and activities of daily living, together with neuropsychiatric symptoms (including behavioural disturbances). These expressions of the pathology of AD impact tremendously not only in terms of the patient, but also the carer and society in general. Considering the high frequency of AD in the aged population, the rapid growth of the elderly population, and the heavy impact in terms of disability, AD has become a major problem for healthcare systems, public health planning and society as a whole. The scale of this problem presents a huge economic burden, in terms of both direct (healthcare system resources) and indirect (unpaid carer services) costs. Thus, the last two decades have witnessed an enormous research effort directed towards discovering the cause of AD with the ultimate hope of developing safe and effective pharmacological treatments.