The real effects of drugs on your brain

Catriona Harvey-Jenner
Photo credit: Issy Muir - Getty Images

From Cosmopolitan

Recreational drugs like cocaine, ecstasy, hallucinogens and cannabis may be illegal in the UK, but that doesn't mean people don't take them. Statistics from the Home Office Crime Survey for England and Wales 2018/19 indicates that around 1 in 5 (20.3%) adults aged 16 to 24 had taken a drug in the last year - that's around 1.3 million people.

We know drugs are addictive - that's part of the reason they're illegal - but what really goes on inside the human brain when you take different substances? Dr Naheed Khan, a Consultant Neurologist at HCA Healthcare UK's London Bridge Hospital, breaks it down for us.

What happens to the brain when you take drugs?

Some organs in the body, such as the skin (which is the largest human organ of them all, Dr Khan tells Cosmopolitan) and bones "repeatedly repair and replace dying and dead cells and so function of that organ is preserved." That isn't the case in the brain, however.

"After injury, brain cells do not have the ability to recover; most brain cells that are injured just die and are lost forever," the neurologist explains. And, well, that's kind of scary.

Different drugs affect the brain in different ways. While some act as stimulants for the brain, others act as depressants. Here's what you can expect, both in the long term and the short term, from the brain when you take recreational drugs:

What happens to the brain when you take cannabis?

"Inhaling cannabis directly interferes with the normal function and workings of the human brain. Cannabis interacts with receptors that lie on the surface of the brain cell, interfering with connections, communication between cells and overall brain function," explains Dr Khan. That's why, if used when the brain is still growing, cannabis can interfere with the normal development of the brain.

Short term effects of cannabis:

  • Stress to the brain, causing a 'high'
  • Heightened senses so that colours appear more vivid and food tastes intense
  • Difficulty with thinking and problem solving
  • Poor learning and reduced performance of old or new tasks
  • Impairment of judgement and reaction times such as the ability to drive safely
  • Intense distress, anxiety, fear, panic attacks and mood swings
  • Acute psychosis such as hallucinations and paranoia

Longer term risks of ingesting cannabis:

"Smoking any type of substance such as tobacco and cannabis is associated with accelerated wear and tear and wrinkling of the brain referred to as cerebrovascular disease, and this is associated with a higher risk of stroke," notes the expert. "The effects are similar to the damage seen in patients with poorly treated or uncontrolled high blood pressure and or diabetes. The MRI of the brain in smokers of any kind of substance will show visible areas of the brain where the small groups of brain cells have died."

Longer term use of cannabis may also result in "irreversible loss of intelligence, especially when there is heavy exposure during teenage years," says Dr Khan. "Loss of memory, in particular verbal memory such as recalling details like phone numbers," is also a risk in the long-run.

Smoking cannabis regularly also comes with an increased risk of developing psychosis, schizophrenia, depression and anxiety - and this risk is higher the younger the user started. "The strongest risk factor is an individual’s susceptibility to developing disease. It is not possible to identify who is at greatest risk; no blood test or brain scan can pick out those who can potentially suffer the severe side effects," adds the neurologist.


What happens to the brain when you take cocaine?

"Dopamine is a normal chemical that acts as a messenger between brain cells in the circuits controlling movement of the body and feeling pleasure. Normally, dopamine is transported back into the cell that released it, naturally shutting down the signals passing between nerve cells and brain circuits," explains Dr Khan.

Cocaine, a powerful stimulant of the brain and highly addictive, interrupts this mechanism by "preventing dopamine from being taken back into the cell, resulting in large amounts of dopamine filling the space between nerve cells. This causes repeated and abnormal stimulation of the cells," says the expert. "The flood of dopamine in the brain’s reward circuit strongly reinforces drug-taking behaviours. As a result, people take stronger and more frequent doses in an attempt to feel the same high, and to obtain relief from the withdrawal."

Short term effects of cocaine:

  • Irritability and hypersensitivity to sight, sound, and touch
  • Paranoia, resulting in extreme and unreasonable distrust of others
  • Bizarre, unpredictable and uncharacteristic or violent behaviour

Longer term risks of taking cocaine:

Perhaps the biggest risk of taking cocaine is the possibility of addiction. "The reward circuit eventually adapts, becoming less sensitive to the increasing levels of dopamine," explains the doctor. Withdrawal symptoms feed the addiction cycle, because repeated exposure leading to "increased displeasure and a negative mood when not taking the drug". This can result in drug seeking behaviour "instead of relationships, food, or other natural rewards," notes Dr Khan.

"Higher doses, more frequent use of cocaine or both are needed to produce the same level of pleasure and relief from withdrawal," adds the expert.

In the long-term, cocaine users may also suffer "poor attention, memory and decision-making; as well as repeated cocaine binges cause increasing bouts of anxiety, paranoia and psychosis where users lose touch with reality and start to have auditory hallucinations, hearing voices and noises that are not real." Cocaine is also linked to malnutrition, due to its power to decrease appetite, causing a breakdown in sensible eating habits and weight loss.

Cocaine-associated stroke is another possibility. As cocaine circulates in the blood, it damages the blood vessel wall by directly damaging the vessel wall like a grenade. Alternatively, a cocaine-induced surge of blood pressure rips through the vessel wall creating a large hole in the blood supply," explains Dr Khan. "A stroke occurs when chunks of the human brain, suddenly loses its blood supply. Large areas of brain tissue, consisting of millions of brain cells, starve, suffocate and die."


What happens to the brain when you take amphetamine MDMA/ecstasy?

"Serotonin is a vital messenger, a neurotransmitter that is released by specific cells in the brain involved in the regulation of mood, emotion, aggression, sleep, appetite, anxiety and memory," says the doctor. "MDMA increases the activity of neurotransmitters dopamine, noradrenalin and especially serotonin. Repeatedly releasing large amounts of serotonin results in the brain effectively 'running out' of serotonin."

Short term effects of amphetamine MDMA/ecstasy:

  • Rise in body temperature (hyperthermia) which causes uncontrolled sweating, dehydration and an imbalance in body salt (sodium)
  • Swelling brain, which is known to cause a coma or epileptic seizures
  • High blood pressure, which can cause headaches, nausea and dizzy spells
  • Lack of appetite
  • Illogical or disorganised thoughts
  • Inability to sleep for days at a time

Longer term risks of taking amphetamine MDMA/ecstasy:

"Longer term effects can include irritability, difficulty concentrating, depression, impulsivity, anxiety and aggression. Disruption of the sleep wake cycle and circadian rhythm; insomnia and difficulty staying asleep," warns Dr Khan.

The neurologist also notes that if hyperthermia, suffered in the short term, is "relentless and does not respond to treatment", this can progress to multiple organ failure and death.


What happens to the brain when you take hallucinogens?

"Hallucinogens are drugs that rapidly and dramatically alter a person’s awareness and perception of their surroundings. Objects and people are seen that do not exist," explains Dr Khan.

There are two main types of hallucinogens: Ketamine and LSD. "Ketamine is used as an anaesthetic in surgery on animals and humans, and causes vivid visual hallucinations and dissociation, feelings of being out of control, disorientation and disconnection from the body and the environment.

"LSD (acid, blotter acid, dots, and mellow yellow) works by temporarily disrupting communication between brain circuits throughout the brain and spinal cord," says the neurologist.

Short term effects of hallucinogens:

  • Hallucinations
  • Intense sensory experiences such as seeing brighter colours
  • Changes in sense of time
  • Insomnia
  • Paranoia
  • Psychosis
  • Bizarre behaviour
  • Panic and anxiety
  • Mood swings
  • Risk of epilepsy

Longer term risks of taking hallucinogens:

Long-term effects tend to be mental-health related. They include persistent psychosis, disorganised thinking, paranoia and mood swings long after discontinuation of the drug. The expert also explains that Hallucinogen Persisting Perception Disorder (HPDD) can occur, which he describes as "unpleasant flashbacks that often happen without warning and may occur within a few days or more than a year after drug use."

According to Dr Khan, damage to the brain or body as a result of taking a drug "can occur at any time from the first dose to that after repeated use. There is nothing that can predict what and when will happen in any one individual," he warns.

"Once a brain cell or chunk of brain has been damaged it will not be able to undergo repair and recovery. The injured brain is lost forever," he reiterates.

Dr Naheed Khan is a Consultant Neurologist at HCA Healthcare UK's London Bridge Hospital.

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