StatPearls
Substance use disorders involve excessive use of nicotine, alcohol, and other illicit substances that leads to social, academic, and occupational impairment. The most common illicit substances seen include cannabis, sedatives, hypnotics, anxiolytics, inhalants, opioids, hallucinogens, and stimulants. The specific factors of substance use disorder consist of abuse, intoxication, and physicalpsychological dependence. Different substances can be classified based on their effects on the central nervous system. These effects vary depending on the substance and can produce everything from increased energy and euphoria to profound sedation. In general, while the effects vary significantly, the initial stages of substance use disorders are characterized by positive reinforcement, where individuals experience a sense of well-being or euphoria with use. As physiological and psychological dependence progresses, an individual experiences negative reinforcement where substances primarily relieve dysphoria and unpleasant withdrawal symptoms.