Physiological Aspects of Drug Use

Mind-altering substances that may result in abuse and dependence are commonly subcategorized into central nervous system (CNS) stimulants (e.g., amphetamine, cocaine, nicotine), CNS depressants (e.g., barbiturates, anxiolytics, alcohol, cannabis), opioids (e.g., heroin, prescription pain medications), and hallucinogens (e.g., LSD, PCP). (It should be noted that cannabis, i.e., marijuana, is often discussed as a separate category.) In the following sections, each of these drug categories are discussed, including their mechanisms of action in the brain, the short-term and long-term physiological effects of abuse, withdrawal symptoms, potential genetic predisposition to abuse, and pharmacological treatments that may assist in their remediation.

Most drugs in the aforementioned categories cause an increase in the neurotransmitter dopamine, particularly within a brain structure called the nucleus accumbens, which is a part of the ...