Narcotics: small molecules (that can) alter “consciousness,” affect “cognition,” and navigate “behavior.” Tobacco, alcohol, and cocaine are self-administered universally for the purpose of mood changing. Many of these chemicals, working at scales one thousand times smaller than the width of a human hair, make users feel invincible and “euphoric.” (Eagleman, 204-205)

Originally, agents that caused (drowsiness) or induced sleep; now, any derivative, natural or synthetic, of “opium” or “morphine” or any substance that has their effects. This term is considered outdated due to imprecision but continues to be widely used. Narcotics are potent inducers of … opioid-related disorders. (MeSH) (They) commandeer the brain's reward circuitry. But something happens after repeated exposure to drugs of abuse - whether heroin, cocaine, whiskey or speed. It induces long-lasting adaptations in (neurochemistry) and architecture, altering how individual neurons in the brain's reward (circuitry) process information and interact with one another. (Nestler, 142-143) Also referred to as 'drugs of abuse.’

Addiction: the compulsive use of a substance, despite its negative or dangerous effects. (PubMedHealth2) Loosing control over use and suffering powerful cravings even after the thrill is gone. (Nestler, 142) The two identifying characteristics are "tolerance" an "dependence." (Lewis, 154) The “dopamine” pathway from the "ventral tegmental area" to the "nucleus accumbens" is critical for addiction. Animals with lesions in these brain regions no longer show interest in substances of abuse. (Nestler, 146) Other brain regions - namely, the "amygdala,"  "hippocampus," and "frontal cortex" - are involved in addiction and communicate back and forth with the ventral tegmental area and the nucleus accumbens. (Nestler, 151) Gene studies as well as "genome-wide association studies" are revealing gene variants that people addicted to various drugs share. These inherited factors must be paired with environmental stimuli for addiction to occur. (Lewis, 154-155) Adjective - 'addictive.'

Dependence: the onset of withdrawal symptoms upon stopping use of the drug. (Lewis, 154) The psychological or physiological need to take a substance in oder to experience its effects or to avoid the effects of its absence. (NCIt) The physical and/or psychological effects produced by the habitual taking of certain drugs, characterized by a compulsion to continue taking the drug. In psychological dependence, repeated use of a drug induces reliance on it for a state of well being and contentment. In physical dependence, withdrawal of the drug causes specific symptoms such as sweating, vomiting, or tremors. (OxfordMed)

Tolerance: a condition that occurs when the body gets used to a medicine so that either more medicine is needed or different medicine is needed. Increased doses are required to produce the same magnitude of effect previously produced by a smaller dose. (NCIt) The need to take more of the drug to achieve the same effects as time goes on. (Lewis, 154) The reduction or loss of the normal response to a drug or other substance that usually provokes a reaction in the body. Drug tolerance may develop after taking a particular drug over a long period of time. In such cases increased doses are necessary to produce the desired effected. (OxfordMed)

Withdrawal: cessation of use or provision of a drug; specifically the interruption of doses of an addictive drug, with resulting craving and physical reactions. (Oxford) Alcohol withdrawal symptoms usually occur within 8 hours after the last drink, but can occur days later. ‘Delirium tremens’ (‘DTs’) is a severe form of alcohol withdrawal that involves sudden and severe mental or nervous system changes. (PubMedHealth2) (Nicotine withdrawal) occurs following suspension of nicotine use. Clinical features may include nicotine craving, irritability, "anxiety," "depression" and increased appetite. The onset of symptoms may be rapid with severity proportional to length and amount of nicotine use. Unsuccessful management of symptoms may prompt a return to nicotine use. Quitting opiates cold turnkey throws the (pain) system suddenly out of balance. As pain circuits are abruptly released from the suppression of opiates they fire wildly and this causes pain and extreme 'hypersensitivity.' Because of this hypersensitivity, normal sensations, light and sound for example, become painful. (Fields, 202)

Amphetamines: a group of drugs that have a marked stimulant action on the central nervous system, alleviating fatigue and producing a feeling of mental alertness and well being. Tolerance to amphetamines develops rapidly, and prolonged use may lead to dependence. (OxfordMed) Enhance “dopamine” (production). (Lambert, 41) Powerful central nervous system stimulants. Amphetamine has multiple mechanisms of action including blocking uptake of (adrenalin) and dopamine. Amphetamine is also a drug of abuse. (NCIt) Editor’s note - street names include 'ice,' 'glass,' 'meth,' 'molly,' 'tina,' and 'MDMA.'

Barbiturates: drugs used to treat “insomnia,” “seizures,” and ‘convulsions,’ and to relieve “anxiety” and tension before surgery. It belongs to the family of drugs called central nervous system depressants. (NCIt) Depressant drugs that cause relaxation and sleepiness. At relatively low doses, barbiturates may cause you to seem like you are drunk, or intoxicated. A barbiturate overdose occurs when someone accidentally or intentionally takes more than the normal or recommended amount of this medication. This is life threatening. A major addiction problem for many people. Most people who take these medications for seizure disorders or pain syndromes do not abuse them. However, those who become addicts usually start by abusing medication prescribed for them or other family members. (PubMedHealth2) Editor's note - street names include 'benzos,' 'downers,' 'reds,' 'blues,' and 'yellow jackets.'

Cocaine: an "alkaloid" that is derived from the leaves of the ‘coca plant’ or prepared synthetically. Causes feelings of exhilaration and may lead to psychologic dependence. Sometimes used as a local anesthetic. (OxfordMed) Affects "norepinephrine" and dopamine levels. (LeDoux, 58) Binds to the dopamine, "serotonin," and norepinephrine “transport proteins” and “inhibits” the “reuptake” of dopamine, serotonin, and norepinephrine into “presynaptic neurons.” This leads to an accumulation of the respective “neurotransmitters” in the “synaptic cleft” and may result in increased “postsynaptic receptor” activation. (NCIt) The effects of cocaine seem to be largely confined to the nucleus accumbens. (Lewis, 155) Interacts with the “reward system” in the brain. Fits lock-and-key into the microscopic machinery of the reward circuits. By plugging into the dopamine system, cocaine and its cousins commandeer the reward system, telling the brain that this is the best possible thing that could be happening. (Eagleman, 205) Editor's note - street names include 'crack,' 'yay,' 'powder,' 'blow,' and 'yayo.'

Hallucinogens: any naturally-derived or synthetic substances that can induce “hallucinations.” (NCIt) Drugs that produce hallucinations. Formerly used to treat certain types of mental illness. (OxfordMed) Drugs capable of inducing “illusions,” hallucinations, “delusions,” paranoid (ideas), and other alterations of mood and thinking. Despite the name, the feature that distinguishes these agents from other classes of drugs is their capacity to induce states of altered perception, thought, and feeling that are not experienced otherwise. (MeSH)

Lysergic Acid Diethylamide (LSD): acts on serotonin receptors. (LeDoux, 58) A potent hallucinogen, but the mechanisms of that effect are not well understood. (MeSH) An illegal hallucinogenic drug. Alternations in sight, hearing, and other senses occur. "Psychotic" effects, "depression," and confusion are common. Tolerance to the drug develops rapidly. Formerly used to aid treatment of certain psychological disorders. (OxfordMed)

Mescaline: hallucinogenic alkaloid isolated from the flowering heads (peyote) of a Mexican cactus used in Indian religious rites and as an experimental (drug). Among its cellular effects are actions at some types of serotonin receptors. It has no accepted therapeutic uses although it is legal for religious use by members of the Native American Church. (MeSH) Also referred to as ‘peyote.’

Psilocybin: a substance being studied in the treatment of anxiety or depression in patients with advanced cancer. It is taken from the mushroom ‘psilocybe mexicana.’ Psilocybin acts on the brain to cause hallucinations (sights, sounds, smells, tastes, or touches that a person believes to be real but are not real). (NCIt) An alkaloid isolated from various (types) of “fungi” with hallucinogenic, antianxiety, and ‘psychoactive’ activities. (NCI2) The major of two hallucinogenic components of the sacred mushroom of Mexico, the other component being ‘psilocin.’ (MeSH) Also referred to as ‘magic mushrooms.’

Opiates: opiates are (narcotics) made from opium or have opium in them. Opiates bind to opioid receptors in the central nervous system. Examples of opiates are "codeine," "heroin," and "morphine." An opiate is a type of analgesic agent. (NCIt) Various drugs derived from the opium poppy and used as narcotics, hypnotics, sedatives, and "analgesics." (Oxford) Substance used to treat pain or cause sleep. Opiates are made from opium or have opium in them. Opiates bind to opioid receptors in the central nervous system. (NCI1) Imbalances of neurotransmitter at synapses result in an imbalanced mind. (Fields, 146) Neurons increase their "excitability" when exposed to opiates for prolonged periods. Therefore more morphine or heroin is necessary to suppress their activity again. (Fields, 201)

Codeine: analgesic derived from morphine but less potent as a pain killer and sedative, and less toxic. (OxfordMed) An opioid analgesic related to morphine but with less potent analgesic properties and mild sedative effects. It also acts centrally to suppress cough. Codeine mimics the actions of endogenous opioids by binding to the opioid receptors at many sites within the central nervous system. (NCIt)

Heroin: a white crystalline powder derived from morphine that is a highly addictive drug of abuse. (OxfordMed) Affects synaptic transmission in the brain. (Fields, 146) An easy drug to 'overdose' on. One's tolerance increases over time, making ever stronger doses necessary to achieve the same effect. The effective dose for a hardened addict may be a fatal dose for someone trying heroin for the first time. (Fields, 200) (According to pain researchers) the source of "chronic pain" is not in pain neurons themselves, but rather in "glia." This insight is cracking the case of drug addiction to heroin and other narcotics. (Fields, 186) Editor's note - street names include 'dragon,' 'black tar,' 'brown sugar,' 'white lady,' and 'tigre.'

Morphine: a potent analgesic used mainly to relieve severe and persistent pain, particularly in terminally ill patients. It also induces feelings of “euphoria.” With regular use tolerance develops and dependence may occur. (OxfordMed) Narcotics like morphine block pain where the pain signals are passed from the "sensory neurons" to the pain circuits inside the spinal cord. (These) neurons have receptors for these narcotic drugs, which inhibit the activity of the neurons. (Fields, 191) Morphine binds to and activates specific opiate receptors, each of which are involved in controlling different brain functions. (NCIt)

Opium: the air-dried (product) from the unripe seed capsule of the opium poppy. Opium has been used as an analgesic. (MeSH) A reddish-brown strong-scented addictive drug prepared from the thickened dried juice of the unripe capsules of the opium poppy flower. (Oxford)

Opioids: substances used to treat moderate to severe pain. Opioids are like opiates, such as morphine and codeine, but are not made from opium. Opioids bind to opioid receptors in the central nervous system. (NCI1) Editor’s note- sometimes used in a broader sense as “narcotics.”

Recreational Drug(s): an illicit narcotic taken on an occasional basis for pleasure. (Oxford) Also referred to as ‘drugs of abuse.’

Alcohol: a chemical substance found in beer, wine, and liquor, and some medicines, mouthwashes, household products, and scented liquid taken from plants. Alcohol contains a "carbon" "atom" attached to a "molecule" made of an "oxygen" atom and a "hydrogen" atom. (NCIt) Produced by the “fermentation” of sugar by "yeast." The alcohol in alcoholic drinks is ‘ethyl alcohol.’ When taken into the body ethyl alcohol depresses activity of the "central nervous system." (OxfordMed) Alcohol affects the "prefrontal cortex." (Lewis, 155) ‘Alcoholic intoxication’ is an acute brain syndrome which results from the excessive ingestion of ethanol or alcoholic beverages. (MeSH)

Marijuana: a recreational drug prepared from the Indian hemp plant. Smoked or swallowed, it produces euphoria and affects "perception" and "awareness," particularly of time. (OxfordMed) The dried leaves and flowering tops of the ‘cannabis sativa' or ‘cannabis indica' plant. Cannabis contains active chemicals called ‘cannabinoids’ that cause drug-like effects all through the body, including the “central nervous system” and the “immune system.” Cannabis may help treat the symptoms of cancer or the side effects of cancer treatment, such as nausea and vomiting, pain, and ‘cachexia’ (loss of body weight and muscle mass). (NCI3) Also referred to as ‘cannabis.’ Editor's note - street names include 'pot,' 'weed,' 'grass,' 'smoke,' 'chronic,' and 'mary jane.'

Tetrahydrocannabinol (THC): the main active ingredient in “marijuana.” ‘Anandamide’ is the human equivalent of THC. (Lewis, 155) An active ingredient in marijuana that is used to treat nausea and vomiting associated with “cancer” “chemotherapy.” (NCIt)

Nicotine: a poisonous alkaloid derived from tobacco, responsible for the dependence of regular smokers on cigarettes. In small doses nicotine has a stimulating effect on the "autonomic nervous system," causing in regular smokers such effects as raised "blood pressure" and "pulse" rate and impaired appetite. Nicotine replacement therapy (nicotine products formulated as chewing gum, skin patches, and nasal sprays) is used as an aid to stop smoking. (OxfordMed) The nicotine in tobacco products causes "lung cancer." Nicotine is highly addictive. The nicotine in tobacco causes addiction and susceptibility to lung cancer, and it delivers the "carcinogens" (Lewis, 155) It is the “agonist” at (nicotine) receptors where it dramatically stimulates "neurons" and ultimately blocks "synaptic transmission." (MeSH)

Tobacco: a plant genus of the family ‘solanaceae.’ Members contain nicotine and other biologically active chemicals; its dried leaves are used for smoking. (MeSH) After harvesting, tobacco leaves are cured, aged, and processed in various ways. The resulting products may be smoked (in cigarettes, cigars, and pipes), applied to the gums (as dipping and chewing tobacco), or inhaled (as snuff). Cured tobacco leaves and the products made from them contain many cancer-causing chemicals, and tobacco use and exposure to secondhand tobacco smoke have been strongly linked to many types of cancer and other diseases. (NCI1)