How THC has changed over the years for the record levels of today
(psycho-active ingredient THC)


References can be found in ‘Cannabis – a general view of its harmful effects’ by Mary Brett at CanSS Ltd on


1. Anyone can become psychotic if they take enough at one time.
2. The incidence of schizophrenia is doubled, possibly due to gene
variations in families.
3. Skunk (80% of UK market) averages 16.2%THC, hash or
Resin (the other 20%) 4 to 6% THC. Herbal cannabis in the
sixties/seventies 1 to 2% THC and virtually unavailable now.
Anti-psychotic CBD present in old cannabis is absent in skunk.
4. Addiction: physical and/or psychological addiction affects 1 in 10.
5. THC persists in brain cells, 50% for a week, 10% still after a
month. All normal brain functioning is disrupted.
6. Learning and memory are badly impaired – academic achievements fall.
A grade ‘D’ student is 4 times more likely to use than one with ‘A’s.
7. Personalities change. Users become inflexible, have fixed ideas and answers to questions, cannot plan their day, can’t solve problems or find words to express themselves. At the same time they feel lonely, miserable and misunderstood. Everyone else is to blame.
8. Cannabis can act as a gateway drug. Ongoing Swedish research on animals is finding that cannabis primes the brain for the use of other drugs, and a 25-year study from birth in New Zealand has found cannabis use to be the single most common factor in progressing to other drugs.
9. Depression can occur, sometimes leading to suicide. Violence is not uncommon due to psychosis or withdrawal. Houses are trashed, parents assaulted, theft of credit cards, money and jewellery quite common.
10. Cancers are caused. Lung, head and neck, children’s cancer, even cancer of the testicles have all been associated with cannabis use.
11. Since THC interferes with the copying of DNA into new cells made in the adult body, white blood cells (our defense against disease) are fewer, sperm and foetal cells are also adversely affected.
12. The cardiac system also suffers. Strokes and heart attacks can occur.

Bursting the Bubble of Marijuana Hype