Researchers from Australian universities have published a first-of-its-kind study which provides evidence for the effectiveness of cannabidiol (CBD) as a treatment for methamphetamine addiction.
While animal studies have previously demonstrated the positive effects CBD can have on opioid and psychostimulant addiction and tobacco dependence, this study is the first to look at the effect CBD treatment has on methamphetamine addiction.
Based on their findings, the researchers from Macquarie University and the University of Sydney are hopeful that future clinical trials could prove CBD to be a novel way of curbing addictive behavior.
Dr Jennifer Cornish, an associate professor at Macquarie University and one of the study’s authors, told PsyPost, “this study has shown that in a preclinical setting, high doses of CBD can act to reduce methamphetamine consumption and also relapse to taking methamphetamine.”
Findings of the study
Fifty-two male Sprague Dawley rats were used in the study, each approximately the same weight to ensure each rat received a uniform CBD dose. Thirty-two underwent a small surgical procedure to implant an intravenous catheter into the right jugular vein.
Once these rats healed, they were trained to self-administer controlled doses of methamphetamines by pulling an active lever which would infuse a small amount of methamphetamine solution into the rat through the catheter. After an active lever press, the lever would become inactive for 20 seconds to safeguard against overdose. If the rat administered the methamphetamines 60 times, the normally 2-hour long study period would be cut short.
After 2-3 weeks of learning this self-administration procedure, the CBD treatment began. Thirty minutes before the normal study period, 16 of the rats were given a dose of either a blank vehicle solution or one of three CBD solutions (20 mg/kg, 40 mg/kg, or 80 mg/kg). By recording the number of lever presses and successful infusions that occurred in the following study period, it was possible to quantify and study the effect of CBD on the rats’ methamphetamine dependence.
The other 16 rats were put into sessions of behavior extinction, designed to terminate their methamphetamine-seeking behavior. After at least two weeks of behavioral extinction, the rats were given meth priming injections intended to trigger the a relapse into methamphetamine-seeking behavior. The same array of vehicle and CBD solutions were then used to study the effect of CBD on the tendency to relapse.
The remaining two groups of ten rats that did not undergo surgery went through similar experiences, but instead of being trained to self-administer methamphetamines through an intravenous catheter, they were trained to self-administer an oral sucrose solution.
It was observed that when given the highest CBD dosage (80 mg/kg) there was a statistically significant reduction in both methamphetamine-seeking behaviors and relapse in the first two groups of rats. This behavior wasn’t seen when the same CBD treatment was given to rats that had been trained to self-administer a sucrose solution, indicating that this was a specific dose-dependent effect of CBD on drug effects, rather than on the body’s general reward mechanisms.
The dangers of methamphetamine addiction
While it may not garner the same amount of attention as the opioid crisis in the US, methamphetamine (meth) abuse is quietly becoming a major issue. States are seeing a rise in the number of meth-related overdoses recorded each year, and US Customs and Border Protection reported a nearly tenfold increase in meth seized between 2010 and 2018.
In the 2017 National Drug Threat Survey, 29.8 percent of responding local agencies named meth as the greatest drug threat to their areas. Meth was also the most common response when asked to name the drug that is most commonly linked to violent crime incidents, and the second-most common response for the question, which drug takes up the greatest amount of law enforcement resources in the area?
Meth abuse and addiction can result in some severe side effects, including psychological problems, aggression, increased risk of hepatitis B and C, hallucinations, and paranoia. Meth overdose is particularly dangerous, as symptoms include difficulty breathing, seizures, and an irregular heartbeat, which can easily lead to death from multiple organ failure, stroke, or a cerebral hemorrhage if medical attention is not sought immediately.
At present, there are no drugs available that can be used to treat meth overdose and addiction, so researching the best preventative care methods, such as novel ways of curbing the addictive behavior, will be key to avoiding methamphetamines becoming a public health emergency on the same scale as the opioid crisis.
But the authors of the recent study are hopeful for the future of methamphetamine addiction treatment. Speaking to PsyPost, one of the paper’s researchers, Dr Jennifer Cornish, said that, “many other studies need to be done in this space prior to the use of CBD in human population of methamphetamine addicts, but this study is a first step for understanding the potential use of CBD treatment in methamphetamine addiction.”
“The major caveats here are that the study is conducted in rodents and uses high doses of CBD,” she continued. “However, there is substantial overlap between the neurobiology of rats and humans, and preclinical studies such as this provide important information on the potential use of new chemicals in human disorders. From this data set we are able to design further experiments that not only discover the effectiveness of CBD as a therapy for methamphetamine addiction, but also the mechanisms by which CBD can reduce methamphetamine intake.”
“By understanding these mechanisms, we can inform the discovery of more targeted therapies that would work like CBD, yet with smaller therapeutic doses.”