Chapter 4: Why Do People Take Drugs?
Continued from part 1.
What is a drug?
“In the context of this book, the definition of a drug is a substance that comes from outside the body, crosses the blood/brain barrier, and has an effect similar to our natural neurotransmitters. (There are other types of drugs – antibiotics, asthma inhalers, warfarin, cough mixture, etc., but we’re not concerned with those here.) Sometimes a drug works by blocking the reuptake sites on the synapses, causing the brain to experience a surge of natural chemicals; cocaine, amphetamines and MDMA all work in this way. Other drugs mimic neurotransmitters (Figure 4.3), communicating with the receptors directly; alcohol and heroin both work like this, and heroin is in fact a much better fit on our endorphin receptors than the natural chemicals we produce, making it a much more effective painkiller.
There are four main classes of drugs taken for pleasure, which we cover in the following four sections.
1. Opioids – opium, heroin, methadone, buprenorphine, codeine
Opium, the latex of the opium poppy, has been used as a painkiller for thousands of years. It contains the natural opiates codeine and morphine, and from these we’ve also derived the synthetic opioids heroin, methadone and buprenorphine. They target the endorphin receptors in the brain, creating a dreamy sense of wellbeing. In medicine, they play an essential role in controlling acute physical pain, and are given to people with traumatic injuries or after surgery, and to enable peaceful deaths for people with terminal illnesses. Opioids also dull psychological pain, and seem to be particularly attractive to people who’ve suffered psychological trauma such as child abuse or living through war.
Opioids and opiates
Opiate: Originally, an opiate was any medicine containing
opium, typically used to relieve pain or to encourage sleep.
More recently it has come to mean any natural drug
extracted from the opium plant; heroin, morphine and
codeine are the best known.
Opioid: any synthetic narcotic drug with physiological effects
similar to morphine’s. It is also used more broadly to include
any such drug, whether natural or synthetic; in this sense all
opiates are opioids, but not opioids are opiates.
In common usage, the two words are now used interchangeably,
or confusingly with exactly the reverse meanings
to those above!
Carrying out normal activities under the influence of opiates is pretty difficult, and even mild opiates such as codeine are not recommended for people driving, or operating heavy machinery. Some are highly addictive, and repeated use leads to physical dependence and powerful withdrawal symptoms. The main harms they do to the body are causing nausea, vomiting and chronic constipation, and the risk of death from stopping breathing in overdose.
Opioids are not good for chronic physical pain, but in spite of this they are widely used for it, which is becoming a major health concern. In the US †more people die now from overdose of prescription opioids than from heroin!
Acute versus chronic conditions
An acute condition is one with a rapid onset, or a short duration,
or both. (Whereas in normal speech “acute” is often used
to mean “severe”, in the medical sense you can have a condition
that is acute but not severe.)
Chronic is the opposite of acute – meaning a condition that
lasts a long time. (Again, you can have a condition that is
chronic but not severe.)
2. Stimulants or “uppers” – cocaine, amphetamine, methamphetamine, caffeine, steroids, khat, mephedrone, tobacco
Stimulants (Table 4.2) release the amines noradrenaline and dopamine. This triggers the “fight or flight” response, makes you feel alert and full of energy, and suppresses the needs for food and sleep. Mild stimulants like caffeine, and nicotine (from tobacco), are part of many people’s day-to-day lives, and some forms of amphetamine like Ritalin can even help people with attention disorders to concentrate on everyday tasks. Drugs at the most powerful end of the scale – cocaine, crack and methamphetamine – over-stimulate the central nervous system and make it difficult to focus on normal activities. The brain becomes locked onto nothing but the drug, and can’t function properly.
Amphetamines have a number of medicinal uses, such as treating attention deficit hyperactivity disorder and narcolepsy (falling asleep without warning), while cocaine is a useful local anaesthetic. Soldiers, students and shift workers who need to stay alert through the night often rely on stimulants, and clubbers use them to keep dancing for hours. For people in highly competitive environments, from street gangs to war zones to high finance, stimulants can help them cope with the psychological stress. Forms that reach the brain very quickly can be highly addictive, and regular stimulant use puts strain on the heart.
3. Depressants or “downers” – alcohol, benzodiazepines, GHB
Depressants activate the GABA receptors, switching off the brain as though it’s preparing to go to sleep. They are useful for decreasing anxiety, relieving insomnia and pain, reducing convulsions, and relaxing muscles in spasm. Alcohol is the most widely used depressant, although it also releases noradrenaline so some of its effects might appear to be like those of a stimulant. GHB is similar to alcohol. Benzodiazepines (which include Valium) are a class of medicines commonly prescribed as sleeping pills or as anxiolytics (anxiety-reducing drugs). Recreationally, all three are often combined with other drugs to coun- teract some of their negative effects.
Depressants seem to promote sociability and enhance mood, probably because they reduce anxiety. At low doses, or when taken as prescribed, they can be compatible with normal life – many elderly people take benzodiazepines nightly for decades to help them sleep – but higher or non-prescribed doses can lead to dependence and trouble stopping. Benzodiazepines have very few physical harms, but can impair memory and increase the risk of falls in the elderly. Alcohol is particularly damaging to the liver and brain because it is intrinsically toxic. (The alcohol in skin wipes sterilizes the skin by killing bacteria on it.) Inside the body alcohol is more harmful because there it breaks down to the even more toxic acetaldehyde.
4. Psychedelics – LSD, mushrooms, ayuesca/ DMT, peyote/mescaline, ibogaine
“Psychedelic” means “mind-manifesting”, and drugs of this sort are still something of a mystery to psychopharmacologists like myself. They act on a special subtype of serotonin receptor (that we discuss in more detail in chapter 16, page 300) which explains the strong pro-social feelings of openness and talkativeness they create. The activity of this receptor also explains the intense visual and transcendental experiences that psychedelics produce. Because they give insights into oneself, and other ways of viewing past and present existence, they have been used by psychotherapists to treat psychological conditions such as post-traumatic stress disorder (PTSD), and to help terminal patients prepare for death. Outside of medical settings, users often take them to explore their own psychologies, and some cultures have long traditions of using them in highly-ritualized and religious settings. They are by far the least addictive class of drug, and have even been used to beat addiction to other drugs (chapter 16, page 309). Although undertaking everyday activities is extremely difficult while under their influence, in one respect they may be easier to integrate into normal life as they rarely lead to compulsive use. They cause very little harm to the body, although with some psychedelics nausea and/or vomiting are common shortly after consumption.”
Stay tuned for part 3. We hope you enjoyed reading these excerpts from David Nutt’s “Drugs Without The Hot Air”. If you are keen to learn more about the science of drugs, do our quiz on drugs and get the (e)book here.