Psychosis Associated With Medical Marijuana: Risk vs. Benefits of Medicinal Cannabis Use

Joseph M. Pierre, M.D.

Los Angeles, Calif.

To the Editor: Over the past 15 years, it has become increasingly evident that cannabis use carries an increased risk for the development of psychosis (1, 2). At the same time, medicinal cannabis (medical marijuana) has been legalized in many states, with minimal restrictions on prescribing indications. The present case illustrates the evolution of a psychotic disorder, in the setting of medicinal cannabis use, in a young man at high risk for psychosis.

“Mr. Z” was a 24-year-old man who was first hospitalized for insomnia, irritability, and aggressiveness 2 years after military service. On admission, he displayed heightened religiosity and mild suspiciousness. Urine toxicology screening revealed cannabinoids, supporting the patient’s endorsed semi-daily cannabis use via water pipe for the past 18 months, without other substance abuse. He was started on quetiapine (100 mg/day), with rapid resolution of symptoms, and discharged after 10 days.

The patient subsequently discontinued quetiapine and was lost to follow-up. Four months later, he presented to a marijuana clinic complaining of chronic pain, insomnia, and anxiety and was given a diagnosis of posttraumatic stress disorder (PTSD) and pain, along with a medical recommendation for cannabis. No psychotic symptoms were elicited. He later explained that he switched from “street” marijuana to medical marijuana in order to obtain a more potent product as well as to avoid illegal activity and getting “ripped off” by drug dealers. He also increased the frequency of his daily use from approximately once to twice daily.

Six months later, Mr. Z was rehospitalized with new-onset auditory hallucinations (multiple voices speaking to each other and urging violence) and delusions (believing that people were tampering with his windows and eavesdropping on his conversations and that he was Jesus Christ). Aripiprazole (15 mg/day) was prescribed, with gradual symptomatic improvement, and then tapered to a lower dose (7.5 mg/day) due to tremor. The patient reported that he believed smoking cannabis helped his chronic pain but that it worsened his psychotic symptoms, such that he wanted help to stop smoking the drug. After 4 weeks, he was discharged to residential substance abuse treatment with only mild, residual psychotic symptoms and a discharge diagnosis of psychotic disorder not otherwise specified, PTSD, and cannabis dependence. At a 3-month follow-up evaluation, while still taking aripiprazole, Mr. Z remained off cannabis and free of psychotic symptoms.

Although cannabis may have some health benefits, it also has a variety of adverse effects, including psychosis, especially among those at high risk (1–3). The patient in the present case was at high risk for psychosis based on attenuated symptoms at first presentation, with evolution of frank psychosis potentially explained by his increased use of cannabis and the greater potency of medicinal relative to “street” cannabis (4). This case underscores the importance of 1) aggressively managing cannabis use in patients at high risk for psychosis and those already suffering from psychosis, 2) apprising physicians who prescribe/recommend medicinal cannabis of its iatrogenic and psychototoxic liability among such individuals, 3) educating the public about the risk of cannabis-induced psychosis, and 4) the need for recent evidence about this public health risk to inform policy decisions about medicinal cannabis in the United States (3).

Footnotes

The author reports no financial relationships with commercial interests.

References

1. Moore THM, Zammit S, Lingford-Hughes A, Barnes TRE, Jones PB, Burke M, Lewis G: Cannabis use and risk of psychotic or affective mental health outcomes: a systematic review. Lancet 2007; 370:319–328

2. Compton MT, Kelley ME, Ramsay CE, Pringle M, Goulding SM, Esterberg ML, Stewart T, Walker EF: Association of pre-onset cannabis, alcohol, and tobacco use with age at onset of prodrome and age at onset of psychosis in first-episode patients. Am J Psychiatry 2009; 166:1251–1257[Abstract/Free Full Text]

3. Hall W: The adverse health effects of cannabis use: What are they, and what are their implications for policy? Int J Drug Policy 2009; 20:458–466[CrossRef][Medline]

4. Di Forti M, Morgan C, Dazzan P, Pariante C, Modelli V, Marques TR, Hadley R, Luzi S, Russo M, Paparelli A, Butt A, Stilo SA, Wiffen B, Powell J, Murray RM: High-potency cannabis and the risk of psychosis. Br J Psychiatry 2009; 195:488–491