Tacrine (also known as Cognex) has been around for a number of years, however its ability to treat the symptoms of mild to moderate Alzheimer's disease has only recently been discovered. The drug will not cure Alzheimer's and it will not stop the disease from it's normal progression, however it has been shown to improve thinking ability in some patients who suffer from this terrible plague. One of the earliest chemical changes that occurs in the brain of Alzheimer's patients is the loss of acetylcholine, which acts as a chemical messenger. Tacrine slows the breakdown of acetylcholine thus improving the quality of life for Alzheimer's patients. The drug may cause liver problems, so blood tests must be conducted on a regular basis on patients using this drug. Side effects include blurred vision, confusion, shortness of breath, and weakness.