Conference Coverage

Conference News Update—American Association for the Advancement of Science


 

References

Is Cannabis the New Frontier of Therapeutics?
Humans have been using cannabis to relieve pain for about 5,000 years, but robust, federally approved research on marijuana’s therapeutic value is just starting to emerge. Researchers who have been studying the plants’ diverse chemical compounds have reported promising initial results, but noted that more studies are needed to understand the best dosing and delivery methods for medical use.

The discovery of more than 100 cannabinoids over the past several years—along with the identification of an innate cannabinoid system in the human brain and the generation of many synthetic cannabinoids in the laboratory—has led to unprecedented insights, researchers said.

Animal models and a limited number of human trials have shown that, in addition to tetrahydrocannabinol (THC), compounds such as tetrahydrocannabivarin, cannabigerol, and cannabidiol have medicinal effects on various disorders, including chronic pain, nicotine addiction, and spasticity. However, it will take much more research to determine the right combinations of compounds to treat particular problems, according to the researchers.

“It’s become clear that many of the other cannabinoids have potential therapeutic activity, but it’s still too early to tell whether that’s going to translate into clinical trial data or not,” said Mark A. Ware, MBBS, MSc, Director of Clinical Research at Alan Edwards Pain Management Unit, and Associate Professor in the Departments of Family Medicine and Anesthesia at McGill University Health Centre in Montreal. “This web of intriguing compounds is what’s making it so exciting and so interesting, but also so challenging,” he said.

“It’s clear that the weight of evidence now is such that cannabinoids are analgesic drugs,” Dr. Ware added. “They’re not powerful analgesic drugs; their effects are modest. But they’re additional tools in the analgesic toolbox that we use when we’re treating patients.”

Roger Pertwee, DPhil, DSc, Chair in Neuropharmacology at the University of Aberdeen in Scotland, who has studied cannabinoids since 1968, highlighted the brain’s own cannabinoid system, which modulates pain, mood, memory, appetite, and more, as an important subject for research. “There are chemicals in our bodies that act like cannabis, and they target the same sites as THC [does],” Dr. Pertwee said. “It raises the question of why on Earth we have these receptors in our bodies.”

In an attempt to answer that question, he and other researchers have begun to uncover a network of cannabis receptors and cannabinoids with complex and sometimes counterintuitive interactions. Some of the receptors relieve pain or nausea without inducing intoxication. Others seem capable of relieving the symptoms of profound psychiatric disorders. Although previous studies have associated cannabis use with schizophrenia, the latest data suggest that some cannabinoids have antischizophrenic effects.

The well-known short-term effects of THC, which include cognitive and motor impairments, do not seem to impart any long-term damage to adult brains, said Igor Grant, MD, Chair of the Department of Psychiatry at the University of California, San Diego.

But he suggests that the compound likely has negative effects on young, developing brains and that marijuana entails an increased risk of motor vehicle crashes, particularly when it is used in combination with alcohol.

More clinical trials with larger numbers of participants are needed to identify the most effective cannabis-based therapies. But researchers believe that such studies are on the horizon, especially given the recent push for marijuana legalization in the United States and elsewhere. Still, government restrictions and the current lack of federal regulation will continue to hamper cannabis research for the time being, they said.

The search for the best delivery system for cannabis is ongoing. A system that vaporizes marijuana without combusting it may offer promise. “What we’re trying to teach patients is that small quantities can achieve the kind of plasma levels that give you pain relief, but stop short of the psychoactive and acute cognitive effects that we’re concerned about,” explained Dr. Ware. “If you adjust the vaporization temperature of the same plant material, it will give off a different profile of cannabinoids.

“This technology to adjust the temperature of the vaporizer to precisely deliver the compounds that you want … or to adjust it to get the right mix [of compounds] … is well within our reach now,” continued Dr. Ware. “Now that we have access to standard, regulated cannabis materials and now that we have labs that can do this work and accurately measure these compounds, we may be able to get somewhere.”

Imaging Helps Researchers Identify Brain Disease at All Ages
Improved imaging techniques are helping researchers detect brain injuries in the womb and clarify the distinctions between aging and Alzheimer’s disease, according to researchers. Functional MRI (fMRI) and techniques like ultrasound are being refined and repurposed to look at ever-smaller structures within the brain and to observe brain activity and metabolism as it happens, investigators said.

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