With new surveys showing alarming rates of self-reported anxiety, scientific interest is growing in the extract’s psychiatric potential

Recently, Karla Ford, daughter of Ontario Premier Doug Ford, shared with her Instagram followers how beyond blissed she was about the “so many amazing” benefits of hemp-derived cannabidiol (CBD) oil, including for soothing anxiety.

While much was made of the post—since hastily deleted—for its violation of federal rules prohibiting the promotion of anything cannabis, largely ignored was whether evidence exists to support cannabidiol for anxiety, or any other mood disorder.

The data isn’t overwhelming. Much of the published research has involved rodents, not humans. However, with new surveys showing alarming rates of self-reported anxiety, scientific interest is growing in the extract’s psychiatric potential.

CBD is a cannabinoid, or chemical compound, found in cannabis plants that comes without the euphoric or mind-altering effects of THC. It doesn’t make people feel high. It’s thought to interact with different receptors in the brain that regulate fear and anxiety-related behaviours.

CBD can be extracted from the flowers and leaves of marijuana or hemp. Hemp contains only trace amounts of THC — 0.3 per cent or less under Canada’s Industrial Hemp regulations — while CBD harvested from marijuana contains varying concentrations of THC.

But is the extract — CBD — better than the whole plant for anxiety, depression or other mood disorders. Do they work best synergistically?

A 2015 review concluded that evidence from human studies “strongly supports” the potential for CBD as a treatment for anxiety, but at oral doses ranging from 300 to 600 mg per day — far above the products sold by provincially licensed retailers or most of the medical marijuana products available from licensed producers (typically 25 mg of CBD per ml of oil).

It also found CBD seemed to be “well tolerated” in doses up to 1500 mg/day, “with no reported psychomotor slowing, negative mood effects or vital sign abnormalities noted,” the team reported.

Still, the review cited fewer than a dozen relevant studies in humans, including one that found CBD reduced anxiety in people put through a mock public speaking task. Participants were given two minutes to prepare a four-minute speech about “the public transportation system of your city.” The study involved just 24 people with generalized anxiety disorder, who were given a single dose of CBD (600 mg of 99.9 per cent pure CBD powder, mixed in with corn oil) or placebo.

A more recent study published last month found CBD helped improve sleep and anxiety in 72 adults treated at a psychiatric clinic in Colorado. Most were given 25 mg a day of CBD in capsule form (for those with anxiety, the dosing was every morning, after breakfast; if the bigger problem was sleep, the CBD was taken after dinner). Side effects were minimal (mainly fatigue) and the CBD seemed better tolerated than routine psychiatric drugs. And, while the doses used were much lower than those reported in earlier studies, they appeared sufficient to elicit an adequate response, the authors wrote in The Permanente Journal.

Still, there was no placebo group, the study was “open-label” — everyone knew they were getting CBD — and most were also taking psychiatric meds and receiving counselling, which seriously limits the ability to make any causal links to CBD treatment, the authors noted.

If nothing else, formal studies on efficacy and dosing are urgently needed, they said, “given the explosion of lay interest in this topic and the rush to market these compounds.”

Other researchers are testing cannabis with varying concentrations of CBD and THC.

In one 2007 study led by McGill University scientists, researchers tested the antidepressant effects of a synthetic THC on rats.

To study “depression” in rats, rodents are placed inside a transparent tank filled with water. Researchers watch to see whether the animals try to climb out, thrash about, swim or simply float, making only the minimal movements needed to keep their heads above water. An immobile rat is a depressed rat.

When the rats were injected with THC, a low dose increased production of serotonin, the same neurotransmitter popular antidepressants known as SSRI’s are said to target. However, when the dose was increased, the serotonin in the rats’ brains dropped below the level of rats in the control group. The anti-depressant effects were completely undone.

Most of the older studies testing the effects of cannabis with different concentrations of THC and CBD on depression and anxiety administered cannabis orally, in a pill or spray, in a laboratory, and in concentrations as low as 1.5 per cent THC, “which is absurdly different from what’s available for sale today,” said Dr. Carrie Cuttler, a clinical assistant professor of psychology at Washington State University.

In a study published last year, Cuttler and her team looked at changes in symptoms of anxiety, depression and stress when people used pot the way many normally use it — smoked, and at home.

They used anonymous data from a mobile Toronto-based app called Strainprint, which lets medical cannabis users track their intake to determine which strains and dosages work best for them.

The Washington group looked specifically at people using pot for depression, anxiety or stress. Their final sample included almost 1,400 people and nearly 12,000 tracked “inhalation” sessions.

Overall, users reported about a 58 per cent reduction in ratings of anxiety and stress, 20 minutes after using cannabis, and about a 50 per cent reduction in ratings of depression.

One puff of weed with a higher CBD/lower THC split was optimal for depression, two puffs of any type of cannabis was sufficient to reduce anxiety and 10 or more puffs of cannabis high in CBD and high in THC was best for stress.

When the researchers looked to see how peoples’ symptoms changed over the longer term, things remained fairly stable for stress and anxiety over the tracked sessions. However, symptoms of depression significantly increased over time.

The concern is that long-term use may desensitize the endocannabiniod system (our brain and body’s natural cannabinoids), which may make people more vulnerable to depression.

“What this really suggests to us is that cannabis is serving like a Band-Aid, and I don’t mean that in any pejorative sense,” Cuttler said. It’s temporarily masking symptoms but not getting at underlying causes.

“It shouldn’t really be used in the long-term,” Cuttler said, adding that cognitive behavioural therapy has proven to have lasting effects for the treatment of depression and anxiety because it fundamentally changes “the thought processes and mechanisms underlying these disorders.”

The Canadian Psychiatric Association has warned that cannabis with high THC content “can result in significantly worse mental health and cognitive outcomes,” including worsening of panic disorder and other anxiety disorders.

However, CBD appears to have countering effects on THC, said Dr. Michael Van Ameringen, a professor with McMaster University’s department of psychiatry and behavioural neurosciences.

“THC, at low levels, can have anti-anxiety properties,” he said. “But once the concentration goes up it actually induces anxiety. When it’s in more equal ratio, the CBD seems to counter any sort of anxiety-generating effects of THC.”

The problem is that the ratio of CBD to THC in plant-based cannabis has changed. Plants are being bred to have ever-higher concentrations of THC.

It’s unclear how CBD might be helping with anxiety, though it’s believed to work on a receptor in the brain that modulates serotonin.

Overall, there is “absolutely minimal” published science to support any cannabis product for anxiety or depression, according to Van Ameringen, who is also a faculty associate with the Michael G. DeGroote Centre for Medicinal Cannabis Research at McMaster. “It’s abysmally awful.”

What’s needed, he said, are properly controlled trials to guide doctors and the public about who is going to benefit, who is not and in what concentrations — pure CBD or high CBD, low THC?

He’s comforted that everything he has seen in the literature suggests CBD is generally quite safe.

“There’s nothing from any animal literature or the literature that’s out there to say it’s toxic,” or dangerous in overdose, he said. Although he does worry about potential drug interactions with medications people might be taking.

However, anti-anxiety drugs like the benzodiazepines Xanax and Ativan have become among the most widely prescribed drugs in the country. They’re not only highly habit forming, if combined with opioids they can lead to rapid and fatal overdoses.

National Post

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