substance use disorder

substance use disorder, recurrent use of drugs or alcohol that impairs psychological and physical function and undermines the affected individual’s ability to perform day-to-day activities and fulfill personal, family, or work responsibilities. Substance use disorders typically affect adolescents and adults and range from mild to severe, the more severe cases ultimately leading to addiction. Alcohol and tobacco use disorders are among the most common types of substance use disorders worldwide.

Although substances can be used occasionally with relatively small risks to mental or physical health, a substance use disorder affecting a person’s well-being and ability to carry out daily tasks can result from chronic, habitual, or patterned use. This is especially the case when individuals use substances that induce tolerance and dependence, which is common with alcohol, cannabis, cocaine, opioids, and tobacco. Repeated use of these substances is associated with changes in brain function such that neurons in the brain adapt to the substance and function normally only when the substance is present in the body. Substances become linked to pleasurable or euphoric experiences via surges of the neurotransmitter dopamine, which is part of the brain’s reward circuit. Over time, the brain develops a craving for the pleasurable or euphoric feeling, driving individuals to use the substance repeatedly.

Recurrent substance use has many different causes. For example, some persons may be genetically predisposed to substance use and addiction. In other cases, underlying psychiatric conditions, such as anxiety or depression, or factors such as environmental or social stressors, including exposure to drugs in adolescence and peer pressure, may influence whether or the extent to which a person uses a substance. Adverse childhood experiences, such as sexual abuse, may also have a role. Persons with substance use disorders can exhibit a wide range of symptoms. Examples include abnormal movements, altered thinking, changes in personality, inability to make decisions, poor judgment, social withdrawal, and sudden changes in mood.

Substance use disorders are diagnosed through evaluation of medical history and behaviours that suggest recurring substance use, as well as through drug testing and prescription drug monitoring. A diagnosis of mild substance use disorder is generally based on the presence of two or more signs or symptoms for a period of at least 12 months, whereas severe cases are diagnosed when the individual exhibits six or more symptoms. Treatment is tailored to the individual. Recovery from substance use disorder may involve detoxification, where the individual gradually stops using the substance, allowing it to clear from the body in a way that minimizes symptoms of withdrawal. Cognitive and behavioral therapies may be used to help individuals unlearn negative behaviours and adopt healthier habits. Medications may also be used to help modify neurotransmitter levels and activity in the brain.