HealthScience & tech The Latest in Medical Cannabis Research: Summer 2018 Josh Kaplan June 19, 2018 Cannabinoids’ roles against infectious disease need the clarity that only prohibition's end can bring. (TK credit)

The pace of cannabis research continues to escalate as we’ve hit midway through 2018. Perhaps unsurprisingly, cannabidiol (CBD) continues to be a hot topic in medicine. Here are five medical research studies from the last quarter that made particularly important strides.

Studies at a Glance:

CBD Treats Brain Changes Caused by Regular Cannabis Use

Regular THC-rich cannabis use can change the way the brain functions. These changes are not always for the better, and they often involve changes to a particular brain region known as the hippocampus.

CBD could be a promising therapeutic or preventative tool to combat some of the long-term negative consequences of THC.

The hippocampus is involved in many brain functions including cognitive performance, control over anxiety, and resilience to stressors. Studies that have imaged the brain by MRI have revealed that regular THC-rich cannabis use alters the structure of the hippocampus. However, it’s becoming increasingly appreciated that CBD can protect the brain against THC’s effects, and therefore, may serve as a protective tool to prevent THC-induced changes or help the brain recover.

Neuroscientists from Australia tested whether CBD (administered in four 50mg capsules/day) affected hippocampal anatomy in regular cannabis consumers. As expected, parts of the hippocampus were smaller than those of cannabis-abstinent subjects. But after 10 weeks of CBD treatment, many of those regions markedly increased in size. Furthermore, those who had more CBD in their plasma at the end of the 10 weeks had greater brain changes.

Importantly, consumers continued to use cannabis throughout the study, suggesting that CBD can rescue some of the harmful effects of THC without abstinence.

CBD’s ability to recover hippocampal size is significant for a number of reasons. For one, it suggests that CBD could be a promising therapeutic or preventative tool to combat some of the long-term negative consequences of THC. These findings also highlight CBD as a promising treatment for a range of clinical disorders such as depression and Alzheimer’s disease that are associated with an impaired hippocampus.

Transdermal CBD for the Treatment of Non-Opioid Addictions

CBD-rich cannabis has emerged as a promising strategy to combat opioid addiction. However, it’s unclear if CBD’s anti-addiction abilities extend beyond opioids to other drugs of abuse.

CBD reduced impulsive decision making and anxiety, two core features the promote drug relapse.

In a recent study, scientists investigated CBD’s ability to protect against factors that promote relapse to alcohol and cocaine use. Several factors promote relapse to drug seeking, including heightened impulsive behavior and profound withdrawal symptoms like anxiety. Since CBD doesn’t have any addictive properties, it could be a promising anti-addiction tool if it helps reduce impulsive decision making and dampen anxiety that stems from drug withdrawal.

This study administered CBD transdermally (i.e., similar to a gel or patch in humans), which makes it unique from the standard injection method often used in rodent research. The scientists found that CBD reduced impulsive decision making and anxiety, two core features the promote drug relapse.

Critically, CBD also reduced the animal’s cocaine or alcohol seeking when returned to the environment they initially received the drug. (That’s like if an alcoholic trying to quit was less likely to drink if returned to their favorite bar.)

Plant-Derived Cannabinoids Improve the Efficacy of Cancer Treatment

Cannabinoid-based cancer treatments just got a supportive boost. One of the limitations in the cannabis-cancer research field is that most studies have been conducted on cultured cells, and not in live rodents or humans.

Mice that received a combination of cannabinoids and radiation therapy had smaller tumors and better survival than untreated animals or those who only received one form of treatment.

A recent study investigated the effect of cannabinoids on cancerous pancreatic and lung tumor growth and animal survival in mice. They sought to answer whether cannabinoids affected the effectiveness of the traditional radiation treatment strategy and identify delivery methods that could optimize cannabinoids’ anti-tumor properties.

Scientists used a novel drug delivery mechanism that slowly released cannabinoids into the body which increases the amount of time they come in contact with the tumor cells. Mice treated with radiation therapy or slowly-released cannabinoids had better overall survival than untreated animals, but those who received both forms of treatment had the best outcomes. Mice that received a combination of cannabinoids and radiation therapy had smaller tumors and better survival than untreated animals or those who only received one form of treatment.

The scientists also found that animals had better outcomes when administered with the slow-release technique, as opposed to being injected directly into the tumor itself. Together, these findings from live animals suggest that cannabinoids have promising abilities to enhance the efficacy of traditional anti-cancer treatment strategies, and these effects can be improved through emerging techniques that slowly release cannabinoids into the body.

CBD’s Fast-Acting, Long-Lasting Antidepressant Effects in Rodents

It is estimated that 20% of the global population is affected by clinical depression. Yet, current pharmacological treatment approaches for depression remain sub-optimal. Nearly a third of patients don’t respond to treatment, and if they do, it takes weeks before their therapeutic effects are felt.

Within the last few years, CBD has been emerged as a promising antidepressant. However, this claim was only supported by a small number of limited studies, and there has been little insight into the changes in brain chemistry that would promote its antidepressant effects.

These antidepressant qualities were observed after just a single dose of CBD, and they persisted for seven days after treatment.

Scientists based largely in Brazil recently published the most comprehensive report on CBD in pre-clinical rodent models of depression. CBD reduced behaviors associated with depression across a range of behavioral tests in different strains of mice and rats, some of which were “depression-prone.” Importantly, these antidepressant qualities were observed after just a single dose of CBD, and they persisted for seven days after treatment.

The antidepressant effects of CBD were associated with changes in brain chemistry in regions linked to depression. CBD increased levels of the brain chemical BDNF in the prefrontal cortex and hippocampus. It also increased the number of connections between brain cells. Both of these factors are reduced in depression and their restoration are hallmarks of effective treatments.

This is the first study to establish CBD’s antidepressant benefits across a range of rodent and behavioral models, and provide mechanistic insight for its effects. CBD’s effectiveness after just a single dose may be an improvement over other strategies that take weeks to kick-in.

Cannabis-Based Pharmaceutical Improves Symptoms of Multiple Sclerosis

Despite the growing body of evidence supporting the benefits of cannabis for clinical use, the field still generally lacks the convincing double-blind, placebo controlled randomized trials that are the gold standard for clinical medicine. One area of medicine where cannabis is making its mark with these clinical trials is in otherwise treatment-resistant medical conditions.

Cannabis used as an add-on therapy led to more than double the number of MS patients who responded positively to treatment and substantially reduced spasticity by the second week of treatment.

A recently completed double-blind, placebo controlled randomized trial compared cannabis (Sativex, which is an oromucosal spray of THC and CBD in a 1:1 ratio) to a placebo for treatment-resistant muscle spasticity in multiple sclerosis (MS). Spasticity is a chronic symptom of MS that becomes more profound with the progression of the disease and greatly worsens the patient’s quality of life. It’s also associated with pain, impaired sleep, bladder dysfunction, and is strongly associated with the development of anxiety and depression.

Cannabis used as an add-on therapy led to more than double the number of MS patients who responded positively to treatment and substantially reduced spasticity by the second week of treatment. It also improved measures associated with spasticity including a reduction in pain and less sleep disruption.

Because cannabis was used as an add-on therapy (ethical concerns necessitate the requirement), it remains unknown if cannabis alone could allay these symptoms, but either way, this study strongly supports the clinical integration of cannabis-based treatment strategies for symptoms of MS.

Lead image: CasarsaGuru/iStock

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Josh Kaplan Josh Kaplan, Ph.D., is an Assistant Professor of Behavioral Neuroscience at Western Washington University. He is a passionate science writer, educator, and runs a laboratory that researches cannabis' developmental and therapeutic effects. View Josh Kaplan's articles