ABSTRACT
This chapter presents information on how and where drugs act in the brain as well as how they can temporarily or permanently change brain function. It also briefly reviews the particular neurobiological effects of commonly abused substances. The chapter focuses on a special classification of drugs psychoactive drugs, which are drugs that alter mental functioning. The mesolimbic dopamine system is the final common pathway whose activation mediates the addictive properties of all psychotropic drugs. The physiological brain changes that occur for people who use and abuse substances may be the most frustrating aspect for family and friends, and probably also for the individual, in terms of why they cannot just stop cold Turkey in using. Because of their ability to alter mood, psychoactive substances are developed and widely used to treat mental disorders. The chapter narrows the lens of focus to the more micro level seeing the physiological impact that substances have on people.
