Biology: The Good and the Bad

The use of psychoactive substances is universal in all cultures throughout history. What are these substances, how do they work and how did we come to use them so ubiquitously?

Psychoactive Substances

A psychoactive drug is any substance, that when taken, can change consciousness, mood, thoughts or behaviour. This occurs as the result of the action of the psychoactive substance on the functioning of the central nervous system.(a) There are three broad classes of psychoactive substances:

  • Depressants; (“downers”), including sedatives, hypnotics, and narcotics. This category includes all of the calmative, sleep-inducing, anxiety-reducing, anesthetizing substances, which sometimes induce perceptual changes, such as dream images, and also often evoke feelings of euphoria. Examples include alcohol, barbiturates, narcotics, cannabis (in low doses) and tranquilisers
  • Stimulants (“uppers”). This category comprises substances that wake one up, stimulate the mind, and may even cause euphoria, but do not affect perception. Examples include nicotine, amphetamines, cocaine, caffeine, ephedra
  • Hallucinogens, which distort how things are perceived and cause sensations not based in external reality. For example: LSD, mescaline, ‘magic mushrooms’, cannabis (in high doses) (b)

Psychoactive substances work by manipulating the synapses in between nerves in the central nervous system. Most of the psychoactive substances, with the exception of alcohol, contain chemicals that closely resemble the brain’s natural neurotransmitters that cross this synapse. (d) Some are able to mimic the effects of neurotransmitters. Others interfere with normal brain function by blocking it, or by altering the way neurotransmitters are stored, released, and removed. Alcohol affects brain function by interacting with multiple neurotransmitter systems, thereby disrupting the delicate balance between inhibitory and excitatory neurotransmitters. (e)

Psychoactive stimulants manifest a wide range of effects which may include:

  • increased alertness
  • awareness
  • wakefulness
  • endurance
  • motivation and productivity

They may

  • evoke feelings of euphoria
  • improve mood
  • reduced anxiety
  • increased arousal, locomotion, heat rate and blood pressure
  • enhance the perception of diminished requirement for food and sleep.

Depressants are considered to be the functional opposites of stimulants (i). They lower blood pressure and heart rate, induce muscle relaxation and sleep, reduce feelings of anxiety or panic, relieve pain by inducing analgesia and can improve mood and sociability.

Crystalline Cocaine

Cocaine is a powerful psychoactive stimulant which is derived or biosynthesised from the leaves of the coca bush (Erythroxylum coca), native to South America.
The most common form of cocaine is cocaine hydrochloride. This is a white, crystalline powder with a bitter, numbing taste. It is extracted from the coca leaves, which in themselves can be chewed or brewed into a tea to achieve similar stimulant effect. Cocaine hydrochloride is most commonly “snorted”. It can also be injected. Some people rub it into the gums, where it is absorbed into the bloodstream. Others add it to a drink or food.
The cocaine hydrochloride can be further processed to produce cocaine base, known as freebase and crack. Freebase is a white powder, while crack generally comes in the form of crystals that range in colour from white or cream to transparent with a pink or yellow hue. Freebase and crack cocaine are usually smoked. (j)

Some of the effects of taking cocaine include:

  • immediate “rush”
  • feelings of euphoria
  • feelings of invincibility
  • a sense of wellbeing
  • increased talkativeness or quiet contemplation and rapture
  • increased confidence and a feeling of invincibility
  • feelings of great physical strength and mental capacity
  • increased libido
  • feeling more awake, reduced need for sleep
  • reduced appetite
  • indifference to pain and localised pain relief
  • increased  energy and increased performance on simple tasks
  •  increased motivation and endurance. (j)

However, it’s not all positive. It can also induce:

  • paranoia, dry mouth, anxiety, agitation and panic
  • unpredictable violent/aggressive behaviour
  • increased blood pressure and heart rate (after an initial slowing)

In the case of cocaine hydrochloride and freebase and crack, prolonged and chronic use can lead to addiction, itching, tachycardia, hallucinations and paranoid delusions. Overdoses cause tachyarrhythmias and marked elevation of blood pressure which can be life threatening. Other deleterious physical effects through intranasal use and chronic smoking are also observed. (k)

Leaves of the coca bush are still chewed by indigenous people of South America. In the thin air at high altitudes, chewing coca leaves increases breathing which increases oxygen intake, helping reduce the effect of altitude sickness, and the other stimulant effects improve energy and power . Beverages made with the leaves are a mild stimulant and are used to effect in much the same way as tea.


Alcohol (of which the active ingredient is ethanol) is produced by the fermentation of grains or vegetables rich in sugar, or by distillation. It is a psychoactive depressant, ingested as an alcoholic beverage into the stomach where it is not digested, but instead is absorbed straight into the bloodstream.

Alcohol has always been tied to the concept of plenty, joyousness, sociability, pleasure- a good life. Alcohol makes us feel good, initially. Alcohol results in the imbiber:

  • being more relaxed
  • feeling more confident, less inhibited
  • showing reduced stress, anxiety, concentration and slower reflexes.

But further drinking starts to:

  • reduce coordination
  • intensify moods
  • slur speech and exhibit confusion, blurred vision, poor muscle control and sometimes aggression.

Further ingestion leads to nausea, vomiting and sleep, and possibly coma and death in cases of alcoholic poisoning. (j)

Alcohol effects every part of the human body: liver (reduces ability for cleansing), the central nervous system (deteriorates starting with intellectual functioning and then motor control), the Blood (blood vessels plug up, causing cell death), the gastrointestinal tract (increased acid in the stomach leading to ulcers), the muscles (leading to cardiomyopathy and arrhythmia) and the endocrine system (under-production of hormones). (m)

The use of alcohol and cocaine can lead to addiction.