Table 4.

Difficulties for the Development of Drugs that Modify the Evolution of AD

Scarcity of AD markers in preclinical stage

Scarcity of markers of AD phenotypes

Difficulty to obtain molecules with selective action on diseased cells

Most drugs will have weak effects since they act only on a part of the etiopathogenic chain

It is necessary to distinguish between symptomatic action and changes in the course of the disease

Need of a prolonged period of observation to prove delay in progression

Need to work with very wide human samples to achieve clinical evidence and statistical signification

High economic cost of trials designed to ascertain modifications in AD evolution