Strong cannabis can cause brain damage.
Skunk is a nasty word for a nasty kind of cannabis - and some of that nastiness can affect your brain. And a study involving people from South London published in February suggested smoking it can triple the risk of a serious psychotic episode.
Most recently we learned powerful 'skunk weed' cannabis causes significant damage to vital nerve fibres linking the two halves of the brain.
The damage occurs in the corpus callosum, the structure that permits the right side of the brain to communicate with the left.
The higher the consumption of the drug, the greater the harm, according to the new evidence. But what effect this might have on users, and whether there's any precise connection with psychosis - known to be associated with strong forms of cannabis - remains unclear.
Scientists feel this reflects a sliding scale where the more cannabis you smoke and the higher the potency, the worse the damage you'll suffer. Two scanning techniques were used to examine 'white matter' in the brains of 56 patients who had reported a first episode of psychosis, and in 43 healthy volunteers.
White matter is the messaging part of the brain made up of the nerve fibres, which carry signals from one part of the brain to another. The corpus callosum happens to be especially rich in cannabinoid receptors, proteins that trigger biochemical effects in response to cannabis.
The study, published in the journal Psychological Medicine, found that frequent use of high-potency cannabis was linked to a biological marker of white matter damage.
Co-author of the report, Dr Tiago Reis Marques, 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."
Lead researcher, Dr Paola Dazzan, said there was an "urgent need" to educate health professionals, the public and policymakers about cannabis risks.
Whether you have psychosis or not, Dr Dazzan said she'd found significant damage to white matter fibres in the brain running alongside the frequent use of strong cannabis.
She added: "As we have suggested previously, when assessing cannabis use it is 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."
There's an urgent need to educate the public