Alzheimer's disease is a brain disease that slowly destroys memory and thinking skills, and eventually, the ability to carry out the simplest tasks. It begins slowly and gets worse over time. The main risk factor for Alzheimer's disease is increased age. As a population ages, the frequency of Alzheimer's disease continues to increase. Currently, there is no cure. There are many compromises in the brain of an Alzheimer's patient. Essentially, three modifications occur: decrease of cholinergic impulse, increased toxic effects caused by ROS, and an inflammatory process in which amyloid plaque participates. This study is a mini-review of Alzheimer's disease, and we report advances in the studies concerning enzymes, and substances or targets of these three processes. Our review was focused on a few biological pathways and involved in the pathophysiology of AD: cholinergic system; oxidative stress; beta-amyloid processing; insulin signaling. We analyzed a large body of evidence coming from biochemical studies and a series of compounds which act on these pathways as alternative treatments for the disease.