Used with the permission of John Clayton
Studies have examined the effects of tetrahydrocannabinol (THC) on the human brain. THC is the primary psychoactive chemical in marijuana (cannabis) plants. One study of teen health in Australia and New Zealand dealt with the effects of THC on depression and suicide. It showed that adolescents using cannabis were 2.5 times as likely to have depression and three times as likely to have suicidal ideas than those who did not use it.
A study of adult daily cannabis users showed they have five times the risk of psychosis compared to non-users. Canadian research has shown that emergency department visits for cannabis syndrome increased by a factor of 13 between 2014 and 2021. Science does not fully understand the effects of THC on the human brain, so users have become test subjects.
Marijuana growers have used selective methods to increase the THC content. In 1995, the total THC by weight of marijuana was around 4%. Today it is 20% or more. Concentrated cannabis products can have THC content as high as 95%. Teen exposure to THC can lead to long-lasting problems with memory and learning, and teens are more likely to become addicted than adults. Very little research is available on the long-term effects of cannabis and THC.
References:
“Transcriptomic diversity of cell types across the adult human brain” in the journal Science
“The teen brain is especially susceptible to the harms of THC” in Science News magazine
