Weighing U.S. data
Most of the data on cannabis come from studies of recreational use, Dr. Daviss said. “We know that it can contribute to symptoms of depression, anxiety, psychosis, and addiction. Younger users are particularly at risk for some of these symptoms. We don’t really know how much of this risk applies to monitored medical use,” he said. “And some states have no requirements for monitoring and modulating the dose, so risk data from these states will be different from states where medical use is more regulated and more similar to standard medical care.”
In addition, data on the benefits of marijuana for psychiatric conditions are limited, Dr. Daviss said. “I have certainly heard directly from patients about how marijuana helps them,” he said. “These comments often suggest improvements in sleep, appetite, mood, and anxiety. “A major concern of psychiatric clinicians is that many people asking for medical cannabis are providing contrived reports of symptoms in an attempt to obtain marijuana for nonmedical (recreational) use,” or to share or sell, he said.
Clinicians also remain concerned that “one’s state medical license or federal [Drug Enforcement Administration] license could be at risk for ‘prescribing’ or ‘recommending’ medical cannabis,” Dr. Daviss said. “Being known as a ‘pot doc’ is not viewed as a career booster and could be seen as a risk factor for enhanced regulatory scrutiny of one’s practice.”
However, “there are many who balance those concerns with a harm reduction approach that acknowledges that drug cartels and gangs are fueled by marijuana sales, resulting in preventable violence and deaths, marijuana of unknown quality or adulteration, and negative criminal justice consequences for what should be viewed as a public health problem rather than a criminal problem,” Dr. Daviss said. “Such a harm reduction perspective may increase the likelihood that some physicians will support the use of either medical cannabis or recreational marijuana.”
As more researchers study medical marijuana, the concerns of psychiatrists will evolve along with the science, Dr. Daviss predicted. Relevant outcomes research would include comparative effectiveness studies such as a randomized, double-blind trials of standardized cannabis formulations versus standard treatment for depression or anxiety, he said.
There’s not enough evidence for specific contraindications for medical marijuana use in psychiatry, Dr. Daviss said. However, most clinicians would say that a psychotic disorder such as schizophrenia is a contraindication, because some users of medical marijuana experience paranoia and other psychotic symptoms, he noted.
Dr. Fichtner agreed, and said “studies do find an association between adolescent marijuana use and later development of psychotic disorders, including schizophrenia.
“Even though authors of such studies extrapolate their findings to public health implications in terms of reducing the number of cases of schizophrenia through prevention of marijuana use, such a cause and effect relationship is far from clear – and such conclusions are unwarranted,” he said.
In fact, he said, at least one small case series found prescription molecular THC to be a helpful adjunct to approved antipsychotic medications in schizophrenia patients who reported symptomatic benefit from previous marijuana use (J Clin Psychopharmacol. 2009 Jun;29[3]:255-8). “Even more compelling,” Dr. Fichtner said, “are data on antipsychotic effects of molecular CBD, an important component of herbal cannabis that does not have THC-like psychoactive effects but has been demonstrated to have anxiolytic properties in a number of human studies.”
Dr. Fichtner said authors of research articles on the association between schizophrenia and cannabis use rarely have grappled with the possibility that patients might experience therapeutic benefits through self-medication. In addition, he said, “there are findings in the literature suggesting that among patients with schizophrenia, those using marijuana may have fewer and more selective cognitive deficits than those who do not use marijuana.”
For his part, Dr. Morhaim also supports an open approach. “All health professionals, psychiatrists included, need to consider cannabis as any other medicine,” Dr. Morhaim said. “It has its uses and side effects; reasons to initiate use and reasons to stop; diagnoses for which it is generally accepted that it works (multiple sclerosis, nausea from cancer chemotherapy, and appetite loss) and ones where [effects are] less clear. The medical-scientific potential, however, is expanding rapidly as the shackles that have blocked proper cannabis research are coming off,” he noted.
Several large studies evaluating the use of cannabis for mental illness are underway, Dr. Morhaim said. As the science expands, recent studies have examined the role of cannabis for treating a range of medical conditions, including Alzheimer’s disease, multiple sclerosis, migraine, and even fracture healing and acne, he said. Still, data remain sparse. For example, a literature review that looked at randomized, clinical trials and meta-analyses tied to marijuana and other cannabinoids, and specific diagnoses found no trials that examined marijuana’s efficacy for treating Tourette disorder, PTSD, or Alzheimer’s disease (J Clin Psychiatry. 2016 Aug;77[8]:1050-64). “Given its rapidly changing legal status, there is an urgent need to conduct double-blind, randomized, placebo- and active-controlled studies on the efficacy and safety of marijuana or its constituent cannabinoids for psychiatric conditions,” wrote Samuel T. Wilkinson, MD, of the department of psychiatry at Yale University, New Haven, Conn., and his associates. Meanwhile, a matched case-control, cross-sectional evaluation of veterans with probable PTSD found no significant differences between cases and controls in PTSD scores and frequency of cannabis use (J Affect Disord. 2016 Jan 15;190:439-42).
Nevertheless, “psychiatrists ought to be familiar with medical cannabis, because they may be taking care of patients who are on it for other (somatic) reasons,” Dr. Morhaim said. “This is just like my work as an emergency doctor; I don’t prescribe psych medicines, but I have to know about them, because patients come to the ER who are on them.”