A3-71 has a different molecular structure and targets different muscarinic receptors. Muscarinic receptors play various roles throughout the body, which is why I believe A2-73 has benefit beyond memory loss. A2-73 interacts with all the muscarinic receptor types, which can help things like your heart, stomach, and muscle movement. A3-71 is designed to specifically target M1 receptors, or those that help with brain function. The molecule is also smaller and has a higher affinity for sigma 1 and M1 receptors, possibly making it more effective. It may not have some of the beneficial side effects that A2-73 has because of this. It has been a long time since I have researched these. A3-71 is what brought me here to invest.