Can Marijuana Treat Schizophrenia?

GW Pharmaceuticals' marijuana study in schizophrenia raises questions over how effective cannabidiol is at treating the disease.

Source: GW Pharmaceuticals.

It's long been held that marijuana use in its traditional form can lead to positive patient experiences, but confirming those personal testimonials in large, placebo-controlled studies has been tough to do.
The difficulty in proving that marijuana can successfully treat disease was hammered home last week when GW Pharmaceuticals (NASDAQ:GWPH) reported results from a schizophrenia trial that raises as many questions as it answers.

Treating the tough-to-treatBecause people suffering from schizophrenia suffer from difficulties in thinking, perceiving the world around them, and controlling their emotional responses, schizophrenia is notoriously difficult to treat.
Currently, treatment comprises of therapy and antipsychotics, such as the megablockbuster Abilify, that bind to neurotransmitters in order to influence the production of dopamine and serotonin, which are associated with a variety of mental disorders.

However, treatment with medication is far from perfect. Because patients taking these drugs have to deal with a range of side effects, such as drowsiness, uncontrollable movements, and weight gain, schizophrenia's symptoms and the medication's side effects can result in many patients failing to take their medication properly. Overall, the pharmacy benefit manager Express Scripts finds that a staggering 42% of mental and neurological disorder patients are non-adherent to their medication and that means there's a big unmet need for new treatment options.

Marijuana's promiseHistorically, a correlation between marijuana use and schizophrenia has led many to think that marijuana can cause schizophrenia. However, evidence is growing that cannabidiol, a non-psychoactive chemical cannabinoid widely found in marijuana's extract, may actually reduce schizophrenia symptoms.
In a recently reported phase 2a trial of GW Pharmaceuticals cannabidiol, patients taking it alongside their current antipsychotic medication saw improvements in various secondary endpoints.

Specifically, cannabidiol patients reported a 20% or greater improvement on their PANSS positive sub-scale at a ratio that was 2.65 greater than patients taking placebo. Cannabidiol use also led to positive but not clinically statistically significant improvements in cognition and responses on a negative-symptoms scale.

Not so fastAt first blush, it would appear that cannabidiol could become a significant alternative to existing schizophrenia treatments someday; however, investors should be wary of that line of thinking.
As fellow Fool Brian Orelli points out, GW Pharmaceuticals' trial endpoints shifted and the company didn't report clinical statistical significance for an endpoint that is to be studied in a larger phase 3 trial.

Instead, the company's trial appears to be a fishing expedition. If so, I'm not sure what GW Pharmaceuticals' caught, especially given that it frequently refers to this study in its press release as "exploratory" before speculating that additional studies in rare childhood mental disorders could be a path to pursue. That may or may not be the right direction for the company to be heading in, but it's hardly the level of conviction an investor would hope to see from one with positive mid-stage trial results in hand.

Looking aheadInvestors looking for a clear-cut victory of cannabidiol that leads to a phase 3 trial are left to wonder what, if any, schizophrenia trials will occur down the road.
That uncertainty, coupled with disappointing trial results for another of its marijuana drugs as a therapy for cancer pain earlier this year, ups the stakes for GW Pharmaceuticals' other marijuana studies, including those targeting childhood epilepsy. Investors should get some insight into its epilepsy program in the next six months.

But, at least for now, it's unclear what GW Pharmaceuticals' plans are for cannabidiol in schizophrenia.