Risks of Cannabis Use in Bipolar Disorder
Cannabis use in bipolar disorder significantly increases the risk of manic symptoms, worsens disease progression, and is associated with approximately 3-fold increased risk for new onset of manic episodes. 1, 2
Psychiatric Risks
- Cannabis use may precipitate or worsen manic symptoms in individuals with pre-existing bipolar disorder, leading to more frequent depressive or manic episodes 1, 2
- High doses of THC are particularly associated with psychotic symptoms, which can exacerbate bipolar psychosis 3
- Cannabis use is associated with younger age at onset of first manic episode and poorer overall outcomes in bipolar disorder 4
- Cannabis consumption increases the risk of rapid cycling and mixed episodes in bipolar patients 4
- Early onset of cannabis use, especially weekly or daily use, strongly predicts future dependence and worse bipolar outcomes 3
Risk of Developing Cannabis Use Disorder
- Approximately 10% of adults with chronic cannabis use may develop cannabis use disorder, characterized by clinically significant impairment or distress 5, 3
- Individuals with bipolar disorder who use cannabis have approximately 30% comorbidity rate of cannabis abuse or dependence 4
- Long-term daily cannabis users may experience withdrawal symptoms after cessation, including irritability, insomnia, headaches, sleep disturbances, appetite changes, and abdominal pain 5, 3
- These withdrawal symptoms typically occur within 3 days after cessation and may last up to 14 days, potentially triggering mood instability 3
Physical Health Risks
- Cardiovascular side effects may include arrhythmias and orthostatic hypotension, which can interact with medications commonly used for bipolar disorder 5, 3
- Long-standing cannabis use can lead to cannabinoid hyperemesis syndrome, characterized by cyclical emetic episodes that are relieved by hot showers 5
- Cannabis smoking affects lung function and is associated with conditions like chronic bronchitis and chronic obstructive pulmonary disease 5, 3
- The increasing potency of cannabis products (average THC concentration almost doubling from 9% in 2008 to 17% in 2017) elevates all health risks 5, 3
Safety Concerns
- Cannabis users are at higher risk of motor vehicle accidents, with drivers who test positive for cannabis being more than twice as likely to be involved in crashes 5
- The percentage of fatal motor vehicle accidents involving cannabis alone increased from 9.0% in 2000 to 21.5% in 2018 5
- Cannabis impairs one's ability to drive because it affects reaction time and coordination 5
- This safety risk is particularly concerning for bipolar patients who may already have impaired judgment during mood episodes 5
Impact on Treatment
- Cannabis use is associated with poorer treatment outcomes in bipolar disorder 4
- Lifetime use of cannabis among bipolar patients appears to be around 70%, making this a common clinical challenge 4
- While some patients report that cannabis relieves symptoms of mania and/or depression, systematic studies supporting these claims are lacking 6
- Cannabis use may interfere with medication adherence and effectiveness in bipolar disorder 2
Clinical Recommendations
- Healthcare providers should engage in open, nonjudgmental conversations about cannabis use with bipolar patients 5
- Screening for cannabis use should be routine in bipolar disorder management 2, 4
- Patients should be educated about the specific risks of cannabis use with bipolar disorder, particularly the increased risk of manic episodes 1, 2
- Treatment should focus on cannabis cessation for patients with bipolar disorder who use cannabis 5, 2
The evidence strongly suggests that cannabis use should be discouraged in individuals with bipolar disorder due to its significant negative impact on disease course, symptom severity, and overall outcomes 1, 2, 4.