Modern insight is informing the old school process of finding chemicals that help more than they harm - this BBC article gives a good idea as to the present state of business: "In tests on mice, the drug, AF267B, reversed the symptoms of memory loss and problems with learning associated with Alzheimer's. ... Further analysis showed it also reduced levels of protein clumps and tangles often found in Alzheimer's patients. ... The drug was developed to activate receptors for a brain chemical called acetylcholine. ... AF267B appears to mimic the action of acetylcholine, binding to its receptors and boosting levels of enzymes involved in breaking down the key protein that forms clumps and tangles in brain cells."