Skunk 
 
 
 
 
 
 Regularly smoking high-strength ‘skunk’ cannabis could damage nerve fibres which transmit messages in your brain, scientists say. 
 
 
 
 Brain scans of drug users found differences in the white matter which connects the two halves of the brain. 
 
 
 
 The same changes were not seen in people who did not use cannabis, or who only smoked less potent strains of the drug. 
 
 
 
 ‘Skunk’ cannabis has much higher levels of THC, the ‘active ingredient’ in cannabis responsible for the ‘high’. 
 
 
 
 Paola Dazzan, a neurobiologist at the Institute of Psychiatry at King’s College London, said, ‘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.’ 
 
 
 
 ‘That reflects a problem in the white matter that ultimately makes it less efficient. We don’t know exactly what it means for the person, but it suggests there is less efficient transfer of information. 
 
 
 
 ‘It is possible that these people already have a different brain and they are more likely to use cannabis. But what we can say is if it’s high potency, and if you smoke frequently, your brain is different from the brain of someone who smokes normal cannabis, and from someone who doesn’t smoke cannabis at all.’ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 Smoking high potency 'skunk-like' cannabis can damage a crucial part of the brain responsible for communication between the two brain hemispheres, according to a new study by scientists from King's College London and Sapienza University of Rome. 
 
 Researchers have known for some time that long-term cannabis use increases the risk of psychosis, and recent evidence suggests that alterations in brain function and structure may be responsible for this greater vulnerability. However, this new research, published today in Psychological Medicine, is the first to examine the effect of cannabis potency on brain structure. 
 
 Exploring the impact of cannabis potency is particularly important since today's high potency 'skunk-like'products have been shown to contain higher proportions of Δ9-tetrahydrocannabinol (THC) than they did around a decade ago. In experimental studies THC has been shown to induce psychotic symptoms and 'skunk-like' products high in THC are now thought to be the most commonly used form of cannabis in the UK. 
 
 Dr Paola Dazzan, Reader in Neurobiology of Psychosis from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King's College London, and senior researcher on the study, said: 'We found that frequent use of high potency cannabis significantly affects the structure of white matter fibres in the brain, whether you have psychosis or not. 
 
 'This reflects a sliding scale where the more cannabis you smoke and the higher the potency, the worse the damage will be.' 
 
 Diffusion Tensor Imaging (DTI), a Magnetic Resonance Imaging (MRI) technique, was used to examine white matter in the brains of 56 patients who had reported a first episode of psychosis at the South London and Maudsley NHS Foundation Trust (SLaM), as well as 43 healthy participants from the local community. 
 
 The researchers specifically examined the corpus callosum, the largest white matter structure in the brain, which is responsible for communication between the left and right hemispheres. White matter consists of large bundles of nerve cell projections (called axons), which connect different regions of the brain, enabling communication between them. 
 
 The corpus callosum is particularly rich in cannabinoid receptors, on which the THC content of cannabis acts. 
 
 The study found that frequent use of high potency cannabis was linked to significantly higher mean-diffusivity (MD), a marker of damage in white matter structure. 
 
 Dr Tiago Reis Marques, a senior research fellow from the IoPPN at King's College London, said: '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.' 
 
 Dr Dazzan added: 'There is an urgent need to educate health professionals, the public and policymakers about the risks involved with cannabis use. 
 
 'As we have suggested previously, when assessing cannabis use it is extremely important to gather information on how often and what type of cannabis is being used. These details can help quantify the risk of mental health problems and increase awareness on the type of damage these substances can do to the brain.' 
 
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 This research was funded primarily by the NIHR Biomedical Research Centre at the South London and Maudsley (SLaM) NHS Foundation Trust and King's College London. 
 
 The study was led by Dr Tiago Reis Marques and Dr Paola Dazzan of the IoPPN at King's, and Dr Silvia Rigucci of Sapienza University of Rome. 

 Study suggests high levels of skunk use may affect the brain’s white matter, making communication between the right and left hemispheres less efficient 
 
 High-strength cannabis may damage nerve fibres that handle the flow of messages across the two halves of the brain, scientists claim. Brain scans of people who regularly smoked strong skunk-like cannabis revealed subtle differences in the white matter that connects the left and right hemispheres and carries signals from one side of the brain to the other. 
 
 
 
 The changes were not seen in those who never used cannabis or smoked only the less potent forms of the drug, the researchers found. 
 
 
 
 Cannabis: what's in a name? Read more 
 
 The study is thought to be the first to look at the effects of cannabis potency on brain structure, and suggests that greater use of skunk may cause more damage to the corpus callosum, making communications across the brain’s hemispheres less efficient. 
 
 Paola Dazzan, a neurobiologist at the Institute of Psychiatry at King’s College London, said the effects appeared to be linked to the level of active ingredient, tetrahydrocannabinol (THC), in cannabis. While traditional forms of cannabis contain 2 to 4 % THC, the more potent varieties (of which there are about 100), can contain 10 to 14% THC, according to the DrugScope charity. 
 
 
 
 “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,” said Dazzan. The corpus callosum is rich in cannabinoid receptors, on which the THC chemical acts. 
 
 
 
 Facebook Twitter Pinterest A DTI image of the corpus callosum, as seen from the side, is shown in red on and superimposed on a background MRI image of the brain. Photograph: Institute of Psychiatry 
 
 “The difference is there whether you have psychosis or not, and we think this is strictly related to the potency of the cannabis,” she added. Details of the study are reported in the journal Psychological Medicine. 
 
 
 
 The researchers used two scanning techniques, magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI), to examine the corpus callosum, the largest region of white matter, in the brains of 56 patients who had reported a first episode of psychosis, and 43 healthy volunteers from the local community. 
 
 
 
 The scans found that daily users of high-potency cannabis had a slightly greater – by about 2% – “mean diffusivity” in the corpus callosum. “That reflects a problem in the white matter that ultimately makes it less efficient,” Dazzan told the Guardian. “We don’t know exactly what it means for the person, but it suggests there is less efficient transfer of information.” 
 
 
 
 The study cannot confirm that high levels of THC in cannabis cause changes to white matter. As Dazzan notes, it is may be that people with damaged white matter are more likely to smoke skunk in the first place. 
 
 “It is possible that these people already have a different brain and they are more likely to use cannabis. But what we can say is if it’s high potency, and if you smoke frequently, your brain is different from the brain of someone who smokes normal cannabis, and from someone who doesn’t smoke cannabis at all,” she said. 
 
 So smoking skunk causes psychosis, but milder cannabis doesn't? Read more 
 
 But even with the uncertainty over cause and effect, she urged users and public health workers to change how they think about cannabis use. “When it comes to alcohol, we are used to thinking about how much people drink, and whether they are drinking wine, beer, or whisky. We should think of cannabis in a similar way, in terms of THC and the different contents cannabis can have, and potentially the effects on health will be different,” she said. 
 
 “As we have suggested previously, when assessing cannabis use, it is extremely important to gather information on how often and what type of cannabis is being used. These details can help quantify the risk of mental health problems and increase awareness of the type of damage these substances can do to the brain,” she added. 
 
 In February, Dazzan and others at the Institute of Psychiatry reported that the ready availability of skunk in south London might be behind a rise in the proportion of new cases of psychosis being attributed to cannabis. 

 High-strength cannabis was found to harm connections between the sides of the brain Gareth Fuller/PA 
 
 Smoking skunk or other strong varieties of cannabis can cause brain damage similar to the effects of concussion, a study suggests. 
 
 The potency of the drug has risen consistently over the past two decades, leaving frequent users at an elevated risk of psychosis and subtler mental health problems. 
 
 Brain scans show that the high-strength cannabis that is increasingly common in the UK does more harm to the “white matter” connecting different parts of the brain than weaker strains. 
 
 Paola Dazzan, reader in the neurobiology of psychosis at King’s College London, said that the region was the mind’s traffic interchange, a tangle of highways carrying crucial instructions from one hemisphere to the other. 
 
 She and her colleagues used magnetic scanners called tractographs to examine the brain…
– A new study raises concerns for those who indulge in potent forms of marijuana. Researchers out of King’s College London and Rome's Sapienza University studied brain scans of 56 patients who had reported an episode of psychosis and 43 healthy volunteers. They found that those who regularly smoked high-strength cannabis showed small changes in the region of the brain that sends messages between the left and right sides, reports the Guardian. The alteration in this region, called the corpus callosum, "reflects a problem in the white matter that ultimately makes it less efficient," says neurobiologist Paola Dazzan. The brains of people who had never used cannabis or smoked less potent forms looked normal, leading researchers to conclude that high-strength versions, like skunk, may damage nerve fibers. The UK Times reports the damage is similar to the effects of a concussion. "We don't know exactly what it means for the person, but it suggests there is less efficient transfer of information," Dazzan says, per Yahoo. So what's doing the damage? Dazzan believes it's the THC in cannabis; less potent varieties contain 2% to 4% THC, while more potent forms contain 10% to 14%. The chemical acts on the cannabinoid receptors found in the corpus callosum, according to a release. Though researchers haven't proven cannabis is responsible for the changes, "it is extremely important to gather information on how often and what type of cannabis is being used," Dazzan says. "These details can help quantify the risk of mental health problems and increase awareness of the type of damage these substances can do." (Potent pot also raises your psychosis risk.)