Michael, age 34, is a heroin addict struggling to get by in Washington DC. He is talking to friends about how he wants to "bang some H" (inject diamorphine) so that he doesn’t go into opiate withdrawal, and says he doesn't want to get high, just "get off sick"," meaning that he can't feel the same effects of the drug due to repeated exposure to opiates and the liver induction and receptor downregulation and degeneration that occur after repeated use. When he "scores" (buys) his dope, he immediately pours a bit of brownish-white powder into a spoon, mixes a small amount of water, and soaks the solution in a bit of cotton wad. Then he pulls the plunger back on the syringe to draw the substance into its route of administration. Upon dosing himself with a 20 unit mixture of heroin, Michael has an instant affect change. He sighs in relief, and the canter of his speech slows from pressured and rapid to near dyslogia. He no longer feels restless, and the dopaminergic projections from the limbic system through the reward pathway are at a false balance because his brain chemistry has been thrown off stasis by addiction.
Take another case of opiate abuse, Sierra, 22, who started taking her grandmother's hyrdrocodone pills to sleep. She doesn't realize the abuse potential for opiates, and takes some pills from the cabinet for five days straight, taking three 25mg pills a day. She feels euphoric and light, has a faint loss of memory. By the time she is on the fifth day, she feels more accustomed to the way that the pills make her stomach feel. She doesn't experience the intensity of withdrawal that Michael did when he was "dopesick" It isn't out of possibility that she could forget her youthful indiscretions and give up taking drugs without much change or effort taken, yet for Michael it is a life-altering event that must happen for him to recover.
A methamphetamine abuser robs a convenience store to fund his habit and ends up doing 8 years in the federal penitentiary. Why? When the hypofrontality of a meth abuser becomes great enough, his judgment is compromised to the point where his actions are different than what he would have done if he had not ingested the substance. Centers of judgement are eroded, and this is compounded by the extreme fatigue and loss of rational thought that occurs on a long enough meth binge. Imbalance in the central nervous system can be severe in cases of methamphetamine abuse. The amount of chemical and stimulation that is unlocked by the reuptake of dopamine when its cells are acted upon by meth is greater than the amount that even the most pleasurable naturally occurring endogenous reaction could produce. Even the genetic coding regions in the nucleus accumbens can change, regulating up or down. Take Kevin 8 years later, now an ex-con on parole who is trying to hold a job and live a healthy lifestyle, avoiding another sentence or conviction by substituting his old habits with marijuana oil extract, as it is legal in his jurisdiction. He manages to avoid the sentence, and gets off parole. But the mundanity of life wears on Kevin, and using friends crop up in the small midwestern town in which he resides. His body and brain remembers, the feelings and associations of his old days smoking meth and hustling the streets. When he and his buddy are smoking his marijuana, the conversation arises that they should get some “ice.” Despite Kevin being completely at a baseline, his pupils dilate and he starts to sweat when he sees the substance. Despite his better judgment, his period of sobriety, and running replacing some of the neurological health and cell creation in an endogenous “runner’s high”, he relapses, because it could not replace the sheer magnitude of reward of meth. Chemical inducement of happiness, grandiosity, excitement, creativity, alertfulness, and sociability that stems from smoking methamphetamine salts is not worth the extreme stress on the brain and body. Kevin died of a heart attack after having stayed up for 5 days injecting meth.
As for stimulants, there are three very commonly used plant alkaloids that are contained within this class of drugs nicotine, caffeine, theophylline, and the more regulated coca plant. The others are synthesized from ephedrine, and include amphetamine, MDMA, and methamphetamine. Most psychostimulants are agonists on the dopamine receptor, with affinity for nicotine being also found widely on nicotinic-acetylcholinergic cells throughout muscle tissue. Caffeine and theophylline are structurally related, and have a milder impact on the body than the other stimulants, as they do not bind readily to dopamine, and instead activate the adenosine a1 and a2 receptors to cause an increase in C-amp, which causes quicker metabolism in the central nervous system producing increased alertfulness, and at higher doses, sweating and jitteriness. Stimulants typically increase the peristaltic and metabolic action of the GI tract, as well as cause weakness, headache, hunger and fatigue. Psychostimulants have been linked to arrhythmias and insomnia.
Depressants are a class of drugs that includes alcohol, benzodiazepines, barbituates (formerly known as sedative-hypnotics). They act on the GABA receptor and stimulate its production, which sends inhibitory signals through the brain and body, causing shallow breathing, dilated pupils, slowed pulse, sleepiness, lack of coordination. Alcohol is known to decrease inhibition at low doses. As the dose related response curve continues, it can disrupt coordination and elocution and production of focused effort. When the alcohol reaches a certain level in the bloodstream, it has innervated the pons and brainstem. Alcohol is the most commonly used depressant, having been fermented as early as 20",000 years ago.
Kyle is a server at a restaurant who drinks after work just to be able just to sleep. He sees people at the restaurant drink to varying degrees, wishing he either do the same at that very second, or just quit for good at last. He rushes out of work ten minutes early to catch last call at the corner party store, and drinks high volume, high gravity Colt 45. He is often shaky by the time he takes his first drink after work, as the balance in GABA and glutamic acid have been thrown off in his brain and body. If Kyle or drinks too much, he could die. If he doesn’t drink at all, he is at risk for a seizure, which eventually comes at the very end of a shift one night. He is rushed to the hospital and treated with an injection of another depressant--phenobarbital.
Hallucinogens are a class of drugs that includes marijuana, psilocybin, ayahuasca, mescaline, di-methyl-triptamine. Isolated in this group is marijuana, as it does not act chemically similar to the triptamines, but instead by activating a g-coupled second messenger system to increase the production of serotonin and dopamine by synthesizing adenylyl cyclase. Effects of marijuana included clouded memory and attention, euphoria and glazing over of the eyes. Several states have written statutes to make it legal for medicinal or recreational use.