Early intervention is key to successful management of Alzheimer disease.

Because of the huge healthcare burden associated with Alzheimer disease (AD) and the increased lifespan in many industrialized countries, the costs associated with AD are expected to reach astronomical proportions in the next 50 years. Diagnosis, treatment and follow-up of AD patients from the earliest stage possible will reduce healthcare costs and increase quality of life. Indeed, progress in our clinical knowledge of AD has led to more reliable diagnostic criteria and diagnostic accuracy, and research efforts are expanding to uncover the earliest manifestations and even the presymptomatic phases of the disease. The initiating and propagating pathologic processes and the anatomic location of the earliest changes will become new targets of research and therapeutic development. The proposed precursor to AD, mild cognitive impairment, is currently under investigation as a possible therapeutic starting point. This paper reviews our current understanding of the early pathology and clinical manifestations associated with mild cognitive impairment and early AD. A discussion of the latest diagnostic techniques as well as promising therapeutic targets for early intervention also will be included.