Screening for Cannabis Use
Physicians should ask all patients about cannabis use, especially adolescents, young adults, or those with concurrent psychiatric or substance use disorders, Dr Kahan urged.
“At baseline or annually, at least ask all patients if they have used any form of marijuana and ask youth or others at higher risk more frequently,” he said.
Be specific in asking these questions, he advised. “Especially with teenagers, you have to ask detailed questions such as, ‘Do you smoke, vape, or eat it? How often do you use: Is it regular or occasional? Do you use it once a week, or every few days, or more frequently? Do you use it primarily on weekends?'”
Moreover, patients should be questioned and screened if they present with symptoms or conditions associated with cannabis use.
Red flags or problematic use include daily or near daily use, social dysfunction, poor function at work or school, repeated unsuccessful attempts to stop or reduce use, and expressions of concern from family or friends, according to Dr Kahan.
Two helpful assessment tools are the CRAFFT Questionnaire,24 which screens for patients who require additional assessment, and the Severity of Dependence Scale,25 which assesses how serious the patient’s problem might be. (Tables 1 and 2)
It is essential to take a careful history because it can be difficult to differentiate between cannabis-induced psychosis and schizophrenia.26 (Table 3)
Treatment Approaches: Pharmacotherapy
Dr Kahan noted that daily or very frequent users often experience withdrawal symptoms on discontinuation of cannabis, including hypersomnia or insomnia, fatigue, anxiety, depression, irritability, and cravings. These symptoms typically come on between 24 and 48 hours of last use and resolve quickly with resumed use. Because withdrawal is so unpleasant, it can have a “negative reinforcing effect” that makes relapse common during that period.
Selective serotonin antidepressants, mixed-action antidepressants, bupropion, buspirone, and atomoxetine are “probably of little value” in treating cannabis dependence.27 Gabapentin, oxytocin, N-acetylcysteine, and nabilone can be helpful for cannabis withdrawal, although the evidence for their use is weak. 27 Dr Raby added that other sympatholytic medications (naltrexone, quetiapine, clonidine, or Prazosin) can also be helpful.
The approach might be different in the case of a cannabis user who has developed psychosis, Dr Raby pointed out, as treatment must target acute psychosis, prevention of future psychosis, treating the underlying disorder (eg, ADHD), and addressing the cannabis dependence itself.
“In an attentional disorder, it is not necessarily helpful to prescribe another stimulant, because once the patient has crossed the threshold of psychosis, the risk for a future psychotic event is high,” he said.
In contrast, introducing an antipsychotic can be helpful, and although several agents in this class might have utility, Dr Raby has found one to be particularly effective.
“Although many prescribers shy away from clozapine, I have had success treating patients in this situation with this medication, especially when there is a family history of schizophrenia,” he continued. “These patients have been able to discontinue after 2 to 3 years without a return to either marijuana or psychosis, provided they do not resume cannabis use in any form.”
In the case of a pattern suggesting atypical depression, which is not uncommon in people with ADHD, he noted, a small dose of antipsychotic might be helpful, together with a monoamine oxidase inhibitor such as tranylcypromine, selegiline, or isocarboxazid.
Clues to the presence of atypical depression include mood reactivity, rejection sensitivity, and seasonal alteration of sleep and appetite.28
In particular, for prominent sleep disturbance, Dr Raby reported success with low doses of chlorpromazine together (or not together) with low-dose quetiapine. “This combination addresses not only sleep but also protects against the return of psychosis and treats the depression in a way that doesn’t exacerbate the attention disorder.”
If the psychosis is brief and transient, low-dose risperidone might “help with sleep, calmness, and provide a buffer,” he added.
Pharmacotherapy is not sufficient to ensure future abstinence and return to optimal functioning, Dr Kahan emphasized.
Dr Raby agreed. “Help [adolescent patients] to understand what effects they were seeking, help them remember the effect of cannabis changes (inducing anxiety and paranoia), and when this happened, and then explain why. It is most important that they must look to this change in effect as a sign that their sanity is at stake.”
One of the most important components of counseling patients is developing a positive, nonjudgmental attitude, demonstrating empathy, and encouraging self-efficacy, Dr Kahan said.
Patients who are at risk for psychosis or other cannabis-induced problems should receive brief counseling consisting of psychoeducation and motivational interviewing, he recommended.
Psychoeducation can include information about the medical and social effects of cannabis use on areas such as academic or employment performance, mood, focus, concentration, social activities, and sleep, Dr Kahan continued.
James McKowen, PhD, Clinical Director, Addiction Recovery Management Service and Assistant Psychologist, Massachusetts General Hospital/Harvard Medical School, Boston, agreed that education is essential but challenging.
“Most young people have no clue, and it can be hard for them to link cause and effect because the onset of the longer-term effects [is] usually insidious and gradual; for example, that marijuana is contributing to poor grades or lack of interest in previously enjoyable activities, such as sports or movies, or that one’s social circle has shrunk to fellow marijuana users and other friendships have fallen to the side,” he told Psychiatry Advisor.
Dr Kahan recommended that clinicians help patients determine realistic goals (eg, reduction in use and eventual abstinence). If patients are not yet ready to change, clinicians should acknowledge the reluctance, remain supportive, keep encouraging the change, and explore the pros and cons of cannabis use.
Dr McKowen emphasized that it is critical to include family members in the therapeutic process for adolescents and young adults, as many college students still live at home or retain close ties with their families.
“Help parents understand addiction and psychosis,” he advised. “Parents are understandably terrified and at a loss what to do. They may worry that their child will be homeless and wandering the streets, especially if they have another relative with a psychotic disorder.”
Parents should also be provided with support and suggestions regarding how to talk to their teenaged children, and what to do if the teenager relapses or refuses to take medication. One helpful resource for parents is Parent CRAFT.
For young people who have moved beyond merely being at risk and are experiencing psychotic symptoms, Dr McKowen recommended cognitive behavioral therapy specifically tailored for psychosis.
Nonpharmacologic approaches to cannabis use in adolescents and young adults can be found in Table 4.
An increasing body of research is linking high-potency cannabis, even when used recreationally, to the risk for psychosis.29 As cannabis becomes legal in more parts of the United States and other countries, and given the paucity of research into its effects and interactions with other substances,30 it is essential for clinicians to be conversant in the types of cannabis that are available, how they are being used, how they affect the brains of adolescents and young adults, and how ongoing use and psychosis can be detected and treated.
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