Cannabis: The Evil Weed?

Cannabis: The Evil Weed? (51:00)

How addictive is cannabis? Does it lead to harder drug use, or is it an underappreciated herbal medicine? Can it cause mental illness? This program explores the science and the public debate surrounding the world’s favorite illegal drug. Tracing the birthplace of the humble plant to Kazakhstan in Central Asia, addiction specialist Dr. John Marsden guides viewers through several topics and issues—including links between THC and schizophrenia; experiments on mice suggesting cannabis-related cognitive impairment; the development of Sativex, a cannabis-derived medicine; and California’s medical dispensary system, which bears some resemblance to the legalization of marijuana. A BBC Production. (51 minutes)

History of Cannabis (04:12)
Almost 1 in 20 of people around the globe use cannabis. The mountains of Kazakhstan may be the birthplace of cannabis. The plant developed botanical TCH as a protection against ultraviolet light. TCH is highly addictive to humans.

Human Response to Cannabis (04:08)
Human response to cannabis is ancient. Neurotransmitters called cannabinoids evolved and became part of the DNA history of all other life forms. Cannabinoid receptors are responsible for the psychological effects of marijuana.

Cannabis/Human Connection (03:31)
Evidence indicates that humans used cannabis at least 3000 years ago in Central Asia. It traveled the Silk Road along with salt and tea. Its progression is unstoppable. Scientists search for cannabis receptors in the human brain.

Psychological Response to Cannabis (02:34)
When cannabinoid receptors are stimulated, they cause nerve cells to reduce the amount of neurotransmitter they release. Brain scans reveal numerous cannabinoid receptors in the human brain, liver, and bones.

Plants and Humans Share Building Blocks (01:56)
The cannabinoid system protects the brain by regulating the other neurotransmitters within in it. Some plants affect human body chemistry because they are made of the same building blocks as humans.

Dark Side of Cannabis (05:07)
Cannabis addiction is not the same as addiction to harder drugs; it is a psychological addiction, not physical. Can cannabis use lead to other, more dangerous drugs? Cannabis exposure does not create enduring biological changes in humans.

Cannabis: Linked to Hard Drugs? (03:45)
Biological reasons cannot account for cannabis users turning to hard drugs. Most people graduate to other drugs for psychological and lifestyle reasons. A teen's behavior changes after a year of smoking a high grade of marijuana.

Cannabis, Schizophrenia, and Memory Loss (05:52)
A diagnosis of schizophrenia is linked with a teen's smoking a high grade of marijuana. Laboratory researchers study links between THC and memory in mice. Young adolescents who smoke cannabis are more likely to suffer memory loss as adults.

Cannabis Users and Schizophrenia (02:00)
The likelihood of anyone developing schizophrenia in adulthood if 1%. Among cannabis users the percent can jump to as high as 6%.

Clear Link Between Cannabis and Schizophrenia Not Found (04:21)
Scientists study both short and long-term links between cannabis and schizophrenia. Cannabis affects the brain's processing centers, creating schizophrenic-like responses.

Medical Use of Cannabis (06:09)
Some people make medical use of marijuana to relieve pain. In the English countryside, marijuana is grown for the first legal product for pain relief.

Chemical Properties of Cannabis (04:40)
A component in cannabis (CBD) has anti-psychotic properties. Achieving the balance between THC and CBD is important to treat different conditions. After 3000 years, new chemical properties of cannabis are being discovered.