Adderall: A combination of amphetamine and dextroamphetamine (both central nervous system stimulants). It has a notably calming and “focusing” effect on patients with attention-deficit hyperactivity disorder (ADHD), particularly children.


Addiction: A chronic, relapsing disease characterized by compulsive drug-seeking and use despite negative consequences and by long-lasting changes in the brain.


Amphetamine: A stimulant drug with effects similar to cocaine.


Anabolic/androgenic steroids: Male hormones, principally testosterone, that are partially responsible for the tremendous developmental changes that occur during puberty and adolescence. Male hormones can accelerate growth of muscle, bone, and red blood cells; decrease body fat; enhance neural conduction (anabolic effects); and produce changes in primary and secondary sexual characteristics (androgenic effects).


Analgesics: A group of medications that reduce pain.


Anesthetic: An agent that causes insensitivity to pain and is used for surgeries and other medical procedures.




Barbiturate: A type of central nervous system (CNS) depressant often prescribed to promote sleep.


Bath salts: An emerging family of drugs containing one or more synthetic chemicals related to cathinone, an amphetamine-like stimulant found naturally in the khat plant


Benzodiazepine: A type of CNS depressant often prescribed to relieve anxiety. Valium® and Xanax® are among the most widely prescribed benzodiazepine medications.


Brainstem: The lower portion of the brain. Major functions located in the brainstem include those necessary for survival, e.g., breathing, heart rate, blood pressure, and arousal.


Buprenorphine: Medication approved by the U.S. Food and Drug Administration in October 2002 for the treatment of opioid addiction.




Cannabidiol: A non-psychoactive cannabinoid that may be useful in reducing pain and inflammation and in controlling epileptic seizures.


Cannabinoid receptor: The receptor in the brain that recognizes and binds cannabinoids that are produced in the brain (anandamide) or outside the body (for example, THC and cannabidiol).


Cannabinoids: Chemicals that bind to cannabinoid receptors in the brain. They are found naturally in the brain (anandamide) and are also chemicals found in marijuana (for example, THC and CBD). They are involved in a variety of mental and physical processes, including memory, thinking, concentration, movement, pain regulation, food intake, and reward.


Cannabis: The botanical name for the plant that produces marijuana.


Carcinogen: A substance that may cause cancer.


Cardiovascular system: The heart and blood vessels.


Central nervous system (CNS): The brain and spinal cord.


Cerebellum: A portion of the brain that helps regulate posture, balance, and coordination.


Cerebral cortex: Region of the brain responsible for higher cognitive functions, including language, reasoning, decisionmaking, and judgment.


Cerebral hemispheres: The two specialized halves of the brain. In right-handed people, the left hemisphere is specialized for speech, writing, language, and calculation; the right hemisphere is specialized for spatial abilities, face recognition, and some aspects of music perception and production.


Cerebrum: The upper part of the brain consisting of the left and right hemispheres.


CNS depressants: A class of drugs (also called sedatives and tranquilizers) that slow CNS function; some are used to treat anxiety and sleep disorders (includes barbiturates and benzodiazepines).


Coca: The plant, Erythroxylon, from which cocaine is derived. Also refers to the leaves of this plant.


Cocaine: A highly addictive stimulant drug derived from the coca plant that produces profound feelings of pleasure.


Cognitive-behavioral treatments: A set of treatments that focus on modifying thinking, motivation, coping mechanisms, and/or choices made by people.


Comorbidity: When two disorders or illnesses occur in the same person, they are called comorbid. Drug addiction and other mental illnesses are often comorbid. Also referred to as co-occurring disorders.


Crack: Slang term for a smokeable form of cocaine.


Craving: A powerful, often overwhelming desire for drugs.




Dependence: A physiological state that can occur with regular drug use and results in withdrawal symptoms when drug use is abruptly discontinued.


Depressants: Drugs that relieve anxiety and promote sleep. Depressants include barbiturates, benzodiazepines, and alcohol.


Detoxification: A process that enables the body to rid itself of a drug. Medically assisted detoxification may be needed to help manage an individual’s withdrawal symptoms. Detoxification alone is not treatment but is often the first step in a drug treatment program.


Dopamine: A brain chemical, classified as a neurotransmitter, found in regions of the brain that regulate movement, emotion, motivation, and pleasure.


Drug: A chemical compound or substance that can alter the structure and function of the body. Psychoactive drugs affect the function of the brain.


Drug abuse: The repeated use of illegal drugs or the inappropriate use of legal drugs to produce pleasure, alleviate stress, and/or alter or avoid reality.


Drugged driving: Driving a vehicle while impaired due to the lingering, intoxicating effects of recent drug use.




Ecstasy (3,4-methylenedioxy-methamphetamine, MDMA): A mood- and perception-altering drug that is chemically similar to hallucinogens and stimulants.


Endogenous: Something produced by the brain or other parts of the body.




Forebrain: The largest division of the brain, which includes the cerebral cortex and basal ganglia. It is credited with the highest cognitive functions.




Hallucinations: Perceptions of something (such as an image or a sound) that does not exist in the real world. Hallucinations usually arise from a disorder of the nervous system or as an effect of a hallucinogenic drug, such as LSD.


Hallucinogens: A diverse group of drugs that alter perceptions, thoughts, and feelings. Hallucinogenic drugs include LSD, mescaline, PCP, and psilocybin (magic mushrooms).


Heroin: A synthetic opioid related to morphine. It is more potent than morphine and is highly addictive.


Hippocampus: An area of the brain crucial for learning and memory.


Hypothalamus: A part of the brain that controls many bodily functions, including feeding, drinking, body temperature regulation, and the release of many hormones.




Ingest: Take food or other substances into the body through the mouth.


Inhalant: Any drug administered by breathing in its vapors. Inhalants are commonly organic solvents, such as glue and paint thinner, or anesthetic gases, such as nitrous oxide.


Inhalation: Taking air or a substance into the lungs by breathing it in through the nose or mouth. Nicotine in tobacco smoke enters the body by inhalation.


Injection: Taking a substance into the skin, subcutaneous tissue, muscle, blood vessels, or body cavities - usually by means of a needle.


Injection drug use: Taking drugs directly into blood vessels using a hypodermic needle and syringe. Also called intravenous drug use.




Limbic system: Area of the brain that is involved with feelings, emotions, and motivations. It is also important for learning and memory.


LSD (lysergic acid diethylamide): A hallucinogenic drug that acts on the serotonin receptor.




Marijuana: A psychoactive drug, usually smoked but sometimes vaporized or ingested, that is typically made from the flowers, leaves, and stems of the female cannabis plant. The main psychoactive ingredient is THC.


Medication: A drug that is used to treat an illness or disease according to established medical guidelines. If the medication contains one or more controlled substances, it must be prescribed by a licensed physician.


Methadone: A long-acting synthetic opioid medication that is effective in treating pain and opioid addiction.


Methamphetamine: An addictive, potent stimulant drug that is part of the larger class of amphetamines.


Methylphenidate (Ritalin®/Concerta®): A CNS stimulant that has effects similar to, but more potent than, caffeine and less potent than amphetamines. It has a notably calming and “focusing” effect on patients with ADHD, particularly children.




Neuron (nerve cell): A unique type of cell found in the brain and throughout the body that specializes in the transmission and processing of information.


Neurotransmitter: A chemical produced by neurons to carry messages to adjacent neurons.


Nicotine: The addictive drug in tobacco. Nicotine activates a specific type of acetylcholine receptor.


Nitrous oxide: A medical anesthetic gas, often used in dentistry, that is also called “laughing gas.” It is abused as an inhalant found in whipped cream dispensers.


Noradrenaline: A neurotransmitter that is made in the brain and influences, among other things, the function of the heart.


Nucleus accumbens: A part of the brain reward system, located in the limbic system, that processes information related to motivation and reward. Nearly all addictive drugs act directly or indirectly on the nucleus accumbens to reinforce drug taking.




Opioids (or opiates): Controlled substances most often prescribed for the management of pain. They are natural or synthetic chemicals similar to morphine that work by mimicking the actions of enkephalin and endorphin (endogenous opioids or pain-relieving chemicals produced in the body).




Pre-frontal cortex: Located in the frontal lobe (one of the four divisions of each cerebral hemisphere) of the brain. This area is important for decisionmaking, planning, and judgment.


Prescription drug abuse: The use of a medication by someone other than for whom it is prescribed, in ways or amounts other than intended by a doctor, or for the experience or feeling it causes.


Propofol: A common type of anesthetic used for surgery.


Psychedelic drug: A drug that distorts perception, thought, and feeling. This term is typically used to refer to drugs with hallucinogenic effects like those of LSD.


Psychoactive: Having a specific effect on the brain.


Psychotherapeutics: Therapeutic drugs that have an effect on brain function; some are used to treat psychiatric disorders. They include antidepressants, mood stabilizers, CNS depressants, stimulants, and opioids.




Relapse: In drug addiction, relapse is the resumption of drug use after an attempt to stop taking it. Relapse is a common occurrence in many chronic disorders, including addiction, that require frequent behavioral and/or pharmacologic adjustments to be treated effectively.


Reward: The process that reinforces behavior or increases its likelihood of recurrence. It is mediated, at least in part, by the release of dopamine into the nucleus accumbens. Human subjects report that reward is associated with feelings of pleasure.


Reward system (or brain reward system): A brain circuit that, when activated, reinforces behaviors. The circuit includes the dopamine-containing neurons of the ventral tegmental area, the nucleus accumbens, and part of the prefrontal cortex.


Route of administration: The way a drug is taken into the body. Drugs are most commonly taken by eating, drinking, inhaling, injecting, snorting, or smoking.


Rush: A surge of pleasure (euphoria) that rapidly follows the administration of some drugs.




Salvia: An herb in the mint family native to southern Mexico that is used to produce hallucinogenic experiences.


Sedatives: Drugs that promote sleep, suppress anxiety, and relax muscles; the National Survey on Drug Use and Health (NSDUH) classification includes benzodiazepines, barbiturates, and other types of CNS depressants.


Serotonin: A neurotransmitter that regulates many functions, including mood, appetite, and sensory perception.


Spice/K2: Dried plant material containing synthetic (or designer) cannabinoid compounds that produce mind-altering effects as well as other compounds that vary from product to product.


Stimulants: A class of drugs that elevates mood, increases feelings of well-being, and increases energy and alertness. Some stimulants, such as cocaine and methamphetamine, produce euphoria and are powerfully rewarding. Other stimulants, such as methylphenidate (Ritalin® and Concerta®) or Adderall® (a mix of amphetamine salts), are often prescribed to treat ADHD.




Tetrahydrocannabinol: See “THC.”


Thalamus: The key relay station for sensory information flowing to the cortex, which is located deep within the brain. It filters important messages out from the background noise, produced by the many signals entering the brain.


THC: Delta-9-tetrahydrocannabinol; the main psychoactive ingredient in marijuana, which acts on the brain to produce marijuana’s psychoactive effects.


Tobacco: A plant widely cultivated for its leaves, which are used primarily for smoking; the tabacum species is the major source of tobacco products.


Tolerance: A condition in which higher doses of a drug are required to produce the same effect achieved during initial use, which often leads to dependence.


Tranquilizers: Drugs prescribed to promote sleep or reduce anxiety; the NSDUH classification includes benzodiazepines, barbiturates, and other types of CNS depressants.




Ventral tegmental area: The group of dopamine-containing neurons that make up a key part of the brain reward system. This region is part of the brain reward pathways that also include the nucleus accumbens and prefrontal cortex.




Withdrawal: Symptoms that occur after regular use of a drug has been abruptly reduced or stopped. Symptom severity depends on the type of drug, the dosage, and how long and how frequently it has been taken.


References: National Institute on Drug Abuse (NIDA)