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High-Strength Cannabis Affects Nerve Fibers In Brain

Many types of cannabis (or marijuana, if you prefer) available on the streets is much stronger than the type puffed away by the hippies of the past. New evidence suggests that the new ‘street grade’ cannabis (‘skunk‘) affects the nerve fibers in the brain. ‘Skunk’ refers to varieties of cannabis that smell strong, drawing a parallel with the smell of a skunk.

A recent study indicates high levels cannabis use could affect the white matter in the brain. White matter is made up of many nerve fibers and cells, and functions to connect grey matter together. The consequence of this is to make communication between the right and left hemispheres of the brain faulty. This claim is based on empirical evidence, taken from brain scans of people who regularly smoke high-strength cannabis.

Looking at cannabis containing higher levels of Δ9-tetrahydrocannabinol (THC) – the active ingredient in cannabis and the one responsible of psychoactive effects – researchers found a progression loss of white matter and they have recorded this as a permanent damage to the brain. This finding is based on 56 patients and it was detected using Diffusion Tensor Imaging (DTI), which is a type of a Magnetic Resonance Imaging (MRI) scan.

Speaking with The Guardian, Paola Dazzan, a neurobiologist at the Institute of Psychiatry at King’s College London, affirmed:

“If you look at the corpus callosum, what we’re seeing is a significant difference in the white matter between those who use high potency cannabis and those who never use the drug, or use the low-potency drug.” The corpus callosum is a thick band of nerve fibers that divides the cerebrum into left and right hemispheres.

For those addicted to smoking cannabis, the though might occur just how much is too much? This may be hard to ascertain, but regularity appears to be a key issue. In a research note, Dr Tiago Reis Marques, who was one of the scientists involved, notes:

“This white matter damage was significantly greater among heavy users of high potency cannabis than in occasional or low potency users, and was also independent of the presence of a psychotic disorder.”

The research was conducted at King’s College London and Sapienza University of Rome. The findings are published in the journal Psychological Medicine, in a paper titled “Effect of high-potency cannabis on corpus callosum microstructure.”

About the author

Tim Sandle

Dr. Tim Sandle is a chartered biologist and holds a first class honours degree in Applied Biology; a Masters degree in education; and has a doctorate from Keele University.