Psychopharmacology is a branch of science that studies the effects that drugs have on the brain, thinking, and behavior. These drugs act on the central nervous system (the brain and spinal cord) and also interact with other body systems, affecting various functions including blood pressure, heart rate and rhythm, breathing rate, and metabolism, the way the body processes and uses nutrients for energy and growth. Drugs studied include medications that are used to treat mental conditions, such as medications to treat depression, anxiety, mania, and psychosis. Drugs of abuse may also be studied, including cocaine, marijuana, hallucinogens, and prescription drugs that may be abused for their affects on mood and consciousness.