Need to talk?

SANEline is open between 4pm to 10pm, 365 days a year

Call 0300 304 7000

More ways to get support

Explore this section

10 Nov 2021

Understanding cannabis – its history and uses

Cannabis, also known as marijuana, weed, hashish, ganja and puff among other names, is a psychoactive drug from the Cannabis plant. Its uses for fabric and rope dates back to the Neolithic age in China and Japan but how and why can long-term use of cannabis lead to dependence, addiction and long-term damage to the brain?

Gone to Pot by Terry Hammond

We recently shared Understanding the impact of cannabis on young minds, an excerpt from Terry Hammond’s book, Gone To Pot – Cannabis: What Every Parent Needs To Know. In this follow-up, he explores the history of cannabis use dating back to the late-1700s and how THC – the psychoactive element of the plant – affects the brain.

In 1999, Terry Hammond’s son was diagnosed with paranoid schizophrenia following excessive exposure to cannabis. This led Terry to highlighting the dangers of cannabis and the need to support families. He has had a distinguished career in mental health. In 2006 he received the Marsh Award in recognition of his mental health and campaigning work.

Cannabis: a “toxic insanity”

During Napoleon Bonaparte’s invasion of Egypt in 1798, alcohol was unavailable as Egypt was an Islamic country. In place of alcohol, Bonaparte’s troops resorted to trying hashish (extracts from the cannabis plant) which they found to their liking. Due to the conspicuous consumption of hashish by the troops, the smoking of hashish and consumption of drinks containing the substance was banned in 1800 because of the adverse effects it was having on troops and locals.

In 1904, Dr George F. W. Ewens, Superintendent of the Punjab Lunatic Asylum, produced a report, Insanity Following the Use of Indian Hemp. It states: “There is a special form of mental disease met with in India, usually classed as toxic insanity, which seems to have direct relation to the excessive use of hemp drugs. The symptoms are entirely mental, among the large number I have now seen, unlike the results of alcohol.”

During the 1920s, the Egyptian government was so concerned about the detrimental effects cannabis was having on the working population, it requested that it be added to the Geneva International Convention on Narcotics Control.

On 28 September 1925, the Dangerous Drug Act became law in the UK. Cannabis was included in the list of dangerous drugs and made illegal. Many countries followed suit and by the end of the 20th century, most developed countries had banned cannabis use.

Human use of cannabis goes back thousands of years, and it is one of the earliest known plants to be cultivated. Cannabis has been used for food, medicine, rope-making, religious ceremonies and for recreational purposes. In first-century China, scholars recorded in the first comprehensive reference guide on herbs and drugs called the Pen-ts’ao Ching, that excessive cannabis smoking caused “seeing the Devil”.

By 100 AD, Chinese physicians believed the drug, if taken in excess, would make one communicate with the spirits and lightens one’s body.

So, what is it that causes an individual to feel a sense of euphoria and make users feel as though they have been possessed?

Dependence, addiction and long-term damage

Cannabis contains a chemical called tetrahydrocannabinol, commonly known as THC, which is the principal psychoactive constituent that gives users the “high”. One of the reasons why cannabis is so potentially dangerous is that when it is ingested, either through inhaling or digesting, it goes straight into the bloodstream and within seconds is absorbed into the brain.

THC interferes with dopamine – a neurotransmitter that acts as a chemical messenger between nerve cells – and distorts the signal, causing the neurotransmitter to send a surge of dopamine to the reward part of the brain, which creates the immediate high.

This sounds good. However, the effects of THC can stay in the brain, not just for hours but days and even weeks. It is not just the high the brain has to contend with, but impaired memory, hand coordination, movement and behaviour. That is why it can be so dangerous to drive a car even days after taking cannabis. If you work with machinery, your chance of an accident also increases.

It affects your movement, concentration and ability to process thought. It’s easy to see that continued use of cannabis with high levels of THC can cause long-term impairment to the communication systems of the brain. Scientists now know with reasonable certainty that long-term use of cannabis, especially with high levels of THC, can lead to dependence, addiction and long-term damage to the brain.

It is cannabis with high levels of THC which is being sold to young people and damaging their brains.

Author, playwright, and campaigner Terry Hammond helped to make our chief executive, Marjorie Wallace, aware of the scandalous treatment of people with mental illness, leading to The Forgotten Illness articles in the Sunday Times and the formation of SANE.

If you would like to know more about the impact cannabis is having on young teenagers and what you can do to protect your children visit:

You may also be interested in My son and cannabis (BBC News)

Post a comment

Please note that you must be registered and logged in to post a comment

Please help us support others in need!

Make a donation

Learn about volunteering

Close menu