Milton Earl Burglass, M.D., M.P.H., M.Div., F.A.A.F.P., F.A.S.A.M., is a neuropsychiatrist at the Zinberg Center for Addictions Studies of the Harvard School of Medicine in Cambridge, Massachusetts.
Why Might Cannabis Be Considered as a Medication with a Potential Use in the Treatment of Psychiatric Disorders?
Three possible applications of cannabis products in psychiatry have been considered and studied: (a) as a substitute for existing pharmaceutical drugs having specific effects and properties for the treatment of the major psychiatric disorders, like depression, psychosis, anxiety, or schizophrenia; (b) as an adjunct to verbal psychotherapy, that is, as an agent that might enhance or facilitate some aspect(s) of verbal psychotherapy; or (c) as a preventive agent the use of which might decrease a person's likelihood of developing a psychiatric disease or disorder. In this chapter we will consider the rationale and evidence for each of these indications.
Cannabis as a Substitute Drug
In modern psychiatry, pharmacological treatments of the major mental disorders are chosen based on the biological or biochemical explanations of the disease, wherein abnormal biochemical states and processes in the brain are thought to express themselves in the signs and symptoms of a disorder. For example, the alterations in mood, cognition, and bodily function seen in major depression are today understood in terms of a chemical imbalance of specific brain hormones, or neurotransmitters, such as serotonin and norepinephrine.
Schizophrenia and other psychoses are understood as expressions of abnormalities involving the neurotransmitter dopamine. Anxiety is thought to involve an abnormality in the GABA (gamma-aminobutyric acid) neurotransmitter system. Hence, drugs used in the treatment of depression have effects that by one of several mechanisms increase the amount of serotonin and or norepinephrine in the brain. Antipsychotic drugs act to decrease the amount of available brain dopamine. Antianxiety drugs either increase the amount of GABA in the CNS (brain and spinal cord) or, due to their chemical structures being similar to GABA, they are able to bind to sites in the central nervous system (Gm) that normally bind to GABA, thereby causing a chain of neurophysiological reactions that results in the suppression of the physical and mental symptoms of anxiety.
Despite their having very specific physiological effects, none of the drugs used in psychiatry are entirely satisfactory. Antipsychotic and antidepressant drugs have undesirable short- and long-term side effects; both require extra work by the liver to be metabolized and may also tax the heart; both can be sedating, and antidepressants are painfully slow to relieve the symptoms of depression (10 to 21 days). Each generation of antianxiety drugs has demonstrated more specific target effects and fewer and less serious side effects. However, their potential for abuse and subsequent dependence remains a substantial concern for both patients and physicians.
Is Cannabis a Better or Safer Drug?
Over the years, despite numerous clinical anecdotes and case reports suggesting that the use of marijuana might improve or reverse a psychiatric disorder, focused research has not supported such a conclusion. Some psychiatric outpatients (with depression, schizophrenia, anxiety) have reported using marijuana to self-medicate both their primary psychiatric symptoms and the unpleasant effects of their prescribed medications and that while doing so they felt they had been able to function better. A survey on substance use by psychotic patients showed that those who preferred marijuana use had a lower hospitalization rate than those who used other substances or no substance (Warner et al. 1994). These patients also scored significantly lower on activation of symptoms and reported beneficial effects on depression, anxiety, insomnia, and physical discomfort. Although intriguing and provocative, these studies were not designed in ways that would justify the conclusion that marijuana use had been responsible for the patients' self-reported improvements. Therefore, cannabis cannot be considered to be a proven alternative pharmacologic treatment for major psychiatric diseases and disorders. Moreover, cannabis does not demonstrate the specific effects on brain chemistry that current psychiatric disease theory would ascribe to an effective treatment agent. Certainly, further research in this area is warranted, but the neuropharmacology of cannabis and mental illness, as presently conceptualized, are not closely related.
Although the principal active ingredient in cannabis, delta-9-tetrahydrocannabinol (THC), has been identified, isolated, and formulated as an orally administered pharmaceutical, in popular culture marijuana is typically smoked. Limited research has suggested that the health consequences and risks (bronchitis, emphysema, cancer, and heart disease) of smoking marijuana are at least as serious as are those associated with smoking tobacco. However, comparable amounts of the two substances are rarely used in practice.
There has been some conflicting evidence to suggest a possible role for marijuana in the treatment of addiction to alcohol and certain opioid drugs (heroin, opium, pain pills, etc.). At least some drug-dependent patients have been found to decrease or stop their use of alcohol or opioids while smoking marijuana regularly. However, no controlled study to date has been conclusive or even persuasive. Moreover, in today's abstinence-oriented environment, a treatment strategy that would substitute one psychoactive, euphorigenic drug (albeit an arguably less harmful one) for another is unlikely to gain the popular, governmental, or professional acceptance necessary to support the required preliminary basic scientific and clinical research.
Cannabis as an Adjunctive Agent
The psychological effects of marijuana are highly variable and extremely subjective. Research has shown that the psychological mind-set of the user and the social setting in which it is used are at least as important as the pharmacology of the substance in determining an individual's experience of marijuana's effects. The frequent subjective reports of "mellowing" and "getting in touch with feelings" described by users of marijuana as one of the drug's major effects has suggested to some patients and psychotherapists its potential usefulness as an adjunct to verbal psychotherapy. On the other hand, some users also report an increase in anxiety, hypervigilance, and paranoia associated with the subjective loss of control induced by the drug. Such effects would clearly be countertherapeutic. Clinicians cannot reliably predict which patients will experience which set of effects from marijuana, nor can users always be certain how the drug will affect them. Although there are scattered case reports in the mental health literature of the facilitating effects of marijuana in verbal psychotherapy, none has been conclusive. Most recently, interest in pharmacological adjuncts to psychotherapy has shifted away from marijuana and focused on a very different, pharmacologically unrelated drug, methylene-dioxy-methamphetamine (MDMA), known as "Ecstasy." Nonetheless, there remains a small group of patient and therapist activists who continue working at various levels to generate interest and support for formal research to study this application of marijuana.
Cannabis as a Preventive Agent
In the 1960s a shifting voice in the counterculture advocated the use of marijuana as an antidote to the mental and emotional "pollution" caused by mainstream culture. The rationale for this was based on the beliefs and teachings of Eastern and mystic philosophy and emerging alternative religious movements. There is as yet no way to responsibly associate the regular use of cannabis products with either a decrease in mental illness or an increase in mental health (howsoever defined) in a population group. Although the smoking of marijuana is a central element in the cultural and religious life of the Rastafarian community in Jamaica, little formal research has been done into the mental health consequences of the practice. Illegality causes its own set of problems by forcing users to engage with drug dealers and maintain secrecy regarding their use because of the potential legal risks.
Conclusion: The Challenge to Researchers and Clinicians
Based upon available research data, clinical reports, and the currently prevailing biochemical understanding of the various forms of mental illness, there is at present no place for cannabis in clinical psychiatry. Moreover, although clarification of many clinical questions and basic issues awaits further research, there is little evidence to suggest that such research will reveal cannabis to be substantially useful in the treatment or prevention of mental illness. Its value as an adjunct to verbal psychotherapy remains to be conclusively demonstrated. Although the drug will likely continue to be used for this purpose by at least a few practitioners, its recognition and endorsement by the major academic and clinical disciplines working in the mental health field is highly problematic.
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