Dementia is a progressive, irreversible decline in cognition that affects a patient's pre-existing level of functioning by definition. Clinical dementia syndrome has a number of etiologies, the most common of which is Alzheimer's disease (AD).
The development of drugs in AD is based on the evolution of the pathophysiology. Disease modification approaches include the targeting of amyloid processing, tau aggregation, insulin signaling, neuro-inflammation and dysfunction of the neurotransmitter, with efforts leading to abandoned expectations and on-going promises. The amyloid cascade is central to many emerging drug therapies, reflecting its dominance in the pathophysiological stage.